Drop clusters_applications_crossplane table

We're cleaning up the deprecated Clusters::Applications code related to Remove clusters_applications_* code (#366573 - closed)

Application code that used this table was removed in Clusters::Applications models removal (#388696 - closed)

In !117460 (merged) we dropped the foreign keys. This was in post deploy migration that has been run.

This MR's purpose is to

• drop the clusters_applications_crossplane table
• move the dictionary files per these instructions

For transparency, this was originally part of a single MR that drops many clusters_applications* tables, but sensing some concern around this I have split them into individual MRs.

Table usage

Thanos Query showing table usage. It's non-zero but very tiny. I don't think it represents application usage with it being this small but would love a Database reviewer's insight on this.

Migration output

main: == [advisory_lock_connection] object_id: 275080, pg_backend_pid: 4543
main: == 20230502182754 DropClustersApplicationsCrossplane: migrating ===============
main: -- drop_table(:clusters_applications_crossplane)
main:    -> 0.0023s
main: == 20230502182754 DropClustersApplicationsCrossplane: migrated (0.0071s) ======

main: == [advisory_lock_connection] object_id: 275080, pg_backend_pid: 4543
ci: == [advisory_lock_connection] object_id: 275260, pg_backend_pid: 4545
ci: == 20230502182754 DropClustersApplicationsCrossplane: migrating ===============
ci: -- drop_table(:clusters_applications_crossplane)
ci:    -> 0.0018s
ci: == 20230502182754 DropClustersApplicationsCrossplane: migrated (0.0140s) ======

ci: == [advisory_lock_connection] object_id: 275260, pg_backend_pid: 4545