Migrate to Gitaly's new runtime directory
This MR migrates away from Gitaly's internal sockets directory in favor of the new runtime directory. This new directory contains all files and directories required by Gitaly, including internal sockets, Git execution environments or Gitaly hooks. The internal sockets directory configuration will eventually be phased out.
Please see gitaly#4113 (closed), gitaly!4415 (merged)
Edited by Patrick Steinhardt