Code and dashboard cleanup after search.gov sitemap launch

[johnnyporkchops]

Summary

What we're after:

• If not already done by search.gov team, delete i14y drawer from search.gov global search affiliate, betafec_api
• Remove references to SEARCHGOV_DRAWER_HANDLE and SEARCHGOV_DRAWER_KEY_MAIN anywhere in code and in Cloud foundry UPS.
• Remove search_indexing.py since we are removing the Wagtail hooks that use that utility to make CRUD requests to 114Y drawer.
• Remove the test affiliates on search.gov : fec_content_s3_dev (fec_content_s3_dev) and DEV.FEC.GOV (dev-fec.gov)

Related PR/Issue:

PR: #5845
Issues:
#5775
#5842

Completion criteria

• References to SEARCHGOV_DRAWER_HANDLE and SEARCHGOV_DRAWER_KEY_MAIN are removed anywhere in code and in Cloud foundry UPS.
• search_indexing.py is removed if found to have no use now
• Test search,gov affiliates are removed
• i14y drawer is deleted from global search affiliate

Tech steps or considerations (optional)

• Delete i14y drawer from global search affiliate on search.gov now or keep it longer unless search.gov already deleted it
• Remove references to SEARCHGOV_DRAWER_HANDLE and SEARCHGOV_DRAWER_KEY_MAIN anywhere in code
• Remove search_indexing.py since we are removing the Wagtail hooks that use this utility to make CRUD requests to 114Y drawer? Or should we keep this temporarily as a reference for using Python Requests, Beautiful Soup etc.? If we keep it temporarily, make sure to comment that it is deprecated so it is not confused as being part of the current search.gov ecosystem
• Remove the test affiliates on search.gov : fec_content_s3_dev (fec_content_s3_dev) and DEV.FEC.GOV (dev-fec.gov) or if we should keep it for future

Future work

After this PR is deployed:

• Remove i14y drawer and test environmental variables from CloudFoundry UPS on all environments #5923

Other future work that may be needed following this issue's completion.