Terrain cache fixes and optimizations

1. Initialize GenericResourceManager::mExpiryDelay with value from settings for all resource managers except for NifFileManager. !3032 (merged) missed that some of them are dynamically created per worldspace and there was not initialization for that. This reduces the number of chunks removed from cache because they are not immediately used.
2. Fix #7557 (closed) by removing "passes" added by https://github.com/OpenMW/openmw/pull/3126. It's kind of mistery what was the author intention but basically on initial loading for Oblivion (AnvilMainEntrance start cell) with view distance covering all cells 537 chunks were requests by preloader with 320 more than once and 177 by first culling with only 129 being in cache. Now it's 177 requested by preloader without any duplicates and 177 by first culling with 100% cache hit.
3. Optimize lookup for a "template" for the terrain chunk by using std::map::lower_bound instead of linear search. This was added by https://github.com/OpenMW/openmw/pull/3126 with linear search is very inefficient.

Test results based on the benchmark from !3101 for Oblivion (4a46d772 - master, 915a8df9 - last commit from MR):

source	key	number	min	max	sum	mean	median	stdev	q95
915a8df9.1693334616.log	Cull traversal time taken Camera 1	8950	0.00034	0.01707	14.95255	0.00167	0.00138	0.00122	0.00361
915a8df9.1693334993.log	Cull traversal time taken Camera 1	8950	0.00034	0.02184	15.16027	0.00169	0.00136	0.00133	0.00375
915a8df9.1693334804.log	Cull traversal time taken Camera 1	8950	0.00034	0.01774	15.22668	0.00170	0.00137	0.00128	0.00374
4a46d772.1693334397.log	Cull traversal time taken Camera 1	8950	0.00000	0.16114	26.66057	0.00298	0.00119	0.01017	0.00726
4a46d772.1693334018.log	Cull traversal time taken Camera 1	8950	0.00000	0.16727	27.48813	0.00307	0.00119	0.01045	0.00785
4a46d772.1693334207.log	Cull traversal time taken Camera 1	8950	0.00000	0.16930	27.70413	0.00310	0.00117	0.01048	0.00779
915a8df9.1693334616.log	Draw traversal time taken Camera 1	8950	0.00056	0.01136	23.28198	0.00260	0.00229	0.00131	0.00506
915a8df9.1693334804.log	Draw traversal time taken Camera 1	8950	0.00058	0.01358	23.46950	0.00262	0.00231	0.00133	0.00503
915a8df9.1693334993.log	Draw traversal time taken Camera 1	8950	0.00060	0.01655	23.93031	0.00267	0.00237	0.00140	0.00516
4a46d772.1693334207.log	Draw traversal time taken Camera 1	8950	0.00000	0.04047	29.19404	0.00326	0.00292	0.00224	0.00760
4a46d772.1693334018.log	Draw traversal time taken Camera 1	8950	0.00000	0.04282	29.32647	0.00328	0.00283	0.00226	0.00800
4a46d772.1693334397.log	Draw traversal time taken Camera 1	8950	0.00000	0.03167	29.45126	0.00329	0.00287	0.00230	0.00806
915a8df9.1693334616.log	Frame duration	8950	0.01569	0.08176	156.88568	0.01753	0.01667	0.00455	0.01689
915a8df9.1693334804.log	Frame duration	8950	0.01582	0.07657	157.22544	0.01757	0.01667	0.00474	0.01692
915a8df9.1693334993.log	Frame duration	8950	0.01567	0.08814	157.27544	0.01757	0.01667	0.00486	0.01690
4a46d772.1693334397.log	Frame duration	8950	0.00000	0.19605	170.13979	0.01901	0.01667	0.01253	0.02722
4a46d772.1693334207.log	Frame duration	8950	0.00000	0.19605	170.38327	0.01904	0.01667	0.01200	0.02905
4a46d772.1693334018.log	Frame duration	8950	0.00000	0.20413	172.03573	0.01922	0.01667	0.01281	0.02944
915a8df9.1693334804.log	GPU draw time taken Camera 1	8950	0.00210	0.01370	27.56236	0.00308	0.00254	0.00121	0.00553
915a8df9.1693334616.log	GPU draw time taken Camera 1	8950	0.00210	0.01231	27.70777	0.00310	0.00260	0.00119	0.00553
915a8df9.1693334993.log	GPU draw time taken Camera 1	8950	0.00221	0.01753	28.22620	0.00315	0.00260	0.00125	0.00564
4a46d772.1693334397.log	GPU draw time taken Camera 1	8950	0.00000	0.01603	33.70045	0.00377	0.00320	0.00166	0.00667
4a46d772.1693334207.log	GPU draw time taken Camera 1	8950	0.00000	0.04125	33.99920	0.00380	0.00318	0.00169	0.00663
4a46d772.1693334018.log	GPU draw time taken Camera 1	8950	0.00000	0.03115	34.07438	0.00381	0.00323	0.00163	0.00663
915a8df9.1693334616.log	Rendering traversals time taken	8950	0.00045	0.01732	17.68347	0.00198	0.00165	0.00128	0.00408
915a8df9.1693334993.log	Rendering traversals time taken	8950	0.00043	0.02207	17.86184	0.00200	0.00164	0.00137	0.00422
915a8df9.1693334804.log	Rendering traversals time taken	8950	0.00046	0.01797	17.94783	0.00201	0.00165	0.00133	0.00418
4a46d772.1693334397.log	Rendering traversals time taken	8950	0.00000	0.16126	30.96960	0.00346	0.00150	0.01018	0.00881
4a46d772.1693334207.log	Rendering traversals time taken	8950	0.00000	0.16942	31.94489	0.00357	0.00152	0.01048	0.00920
4a46d772.1693334018.log	Rendering traversals time taken	8950	0.00000	0.16735	31.96102	0.00357	0.00151	0.01046	0.00913
915a8df9.1693334616.log	world_time_taken	8950	0.00005	0.07803	15.28416	0.00171	0.00029	0.00683	0.00136
915a8df9.1693334804.log	world_time_taken	8950	0.00005	0.07141	15.52198	0.00173	0.00029	0.00701	0.00134
915a8df9.1693334993.log	world_time_taken	8950	0.00005	0.08513	15.60633	0.00174	0.00030	0.00710	0.00136
4a46d772.1693334207.log	world_time_taken	8950	0.00000	0.23707	18.54296	0.00207	0.00023	0.01010	0.01072
4a46d772.1693334397.log	world_time_taken	8950	0.00000	0.18815	18.97701	0.00212	0.00023	0.01063	0.01092
4a46d772.1693334018.log	world_time_taken	8950	0.00000	0.22600	20.31801	0.00227	0.00023	0.01132	0.01230

Tested with:

[Terrain]
distant terrain = true
object paging = false

[Camera]
viewing distance = 8192000

[Cells]
preload num threads = 1
pointers cache size = 100
preload distance = 20480
preload cell cache max = 512
preload cell expiry delay = 300
prediction time = 5
cache expiry delay = 10