chore: remove all in one dbless legacy manifest

[pmalek]

What this PR does / why we need it:

This removes the legacy (already deprecated) dbless, all in one manifest, which deployed Kong Gateway and KIC in the same Pod.

Which issue this PR fixes:

Part of #4671

Special notes for your reviewer:

PR Readiness Checklist:

Complete these before marking the PR as ready to review:

• the CHANGELOG.md release notes have been updated to reflect any significant (and particularly user-facing) changes introduced by this PR

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (0cf6c77) 77.6% compared to head (d2a6968) 75.4%.
Report is 2 commits behind head on main.

❗ Current head d2a6968 differs from pull request most recent head c545c71. Consider uploading reports for the commit c545c71 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #4866     +/-   ##
=======================================
- Coverage   77.6%   75.4%   -2.3%     
=======================================
  Files        164     164             
  Lines      18409   18409             
=======================================
- Hits       14301   13896    -405     
- Misses      3288    3703    +415     
+ Partials     820     810     -10     

see 15 files with indirect coverage changes

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