chore: Keep autogenerated message in upstream.yaml for HA manifests

[jannfis]

Restore the "This file is autogenerated..." message in upstream.yaml of the HA manifest generation, which was removed by accident in PR #3356

Checklist:

• (c) this does not need to be in the release notes.
• The title of the PR states what changed and the related issues number (used for the release note).
• I've updated both the CLI and UI to expose my feature, or I plan to submit a second PR with them.
• Optional. My organization is added to USERS.md.
• I've signed the CLA and my build is green (troubleshooting builds).

[codecov]

Codecov Report

Merging #3367 into master will increase coverage by 0.06%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3367      +/-   ##
==========================================
+ Coverage   40.43%   40.50%   +0.06%     
==========================================
  Files         175      175              
  Lines       19059    19085      +26     
  Branches      237      237              
==========================================
+ Hits         7707     7730      +23     
- Misses      10418    10419       +1     
- Partials      934      936       +2     

Impacted Files	Coverage Δ
server/account/account.go	70.31% <0.00%> (+4.62%)	⬆️

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