deprecate(related_issues): Drop support for doing all types of related issues

[armenzg]

This is a follow-up to #70504. Once the UI stops using this approach we will merge this change.

This got temporarily reverted in #70606 since we had to revert the UI PR.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.03%. Comparing base (9c8f38e) to head (1e3a301).
Report is 6 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #70793      +/-   ##
==========================================
+ Coverage   80.00%   80.03%   +0.02%     
==========================================
  Files        6507     6504       -3     
  Lines      290809   290575     -234     
  Branches    50125    50090      -35     
==========================================
- Hits       232669   232568     -101     
+ Misses      57704    57570     -134     
- Partials      436      437       +1     

Files	Coverage Δ
src/sentry/api/endpoints/issues/related_issues.py	100.00% <100.00%> (+8.33%)	⬆️
src/sentry/issues/related/__init__.py	100.00% <ø> (+41.66%)	⬆️

... and 153 files with indirect coverage changes

[sentry-io]

Suspect Issues

This pull request was deployed and Sentry observed the following issues:

• ‼️ MultiValueDictKeyError: 'type' /api/0/issues/{issue_id}/related-issues/ View Issue

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