Fix v3.6 deprecation notices

[ivanvc]

This pull request fixes deprecation comments in server/embed configuration options. I also did a pass to the whole repository to identify issues with deprecation comments.

From #18023 (comment).

Please read https://github.com/etcd-io/etcd/blob/main/CONTRIBUTING.md#contribution-flow.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.87%. Comparing base (f30cbaa) to head (1f4b3cd).
Report is 4 commits behind head on main.

Additional details and impacted files

Files with missing lines	Coverage Δ
api/v3rpc/rpctypes/error.go	90.47% <ø> (ø)
server/embed/config.go	80.11% <ø> (ø)
server/features/etcd_features.go	60.00% <ø> (ø)

... and 23 files with indirect coverage changes

@@            Coverage Diff             @@
##             main   #19401      +/-   ##
==========================================
- Coverage   68.91%   68.87%   -0.05%     
==========================================
  Files         420      420              
  Lines       35759    35759              
==========================================
- Hits        24645    24628      -17     
- Misses       9691     9706      +15     
- Partials     1423     1425       +2     

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[ahrtr]

LGTM

Thanks @ivanvc for the quick fix.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ahrtr, ivanvc

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[ahrtr]

/cherry-pick release-3.6

[k8s-infra-cherrypick-robot]

@ahrtr: new pull request created: #19402

In response to this:

/cherry-pick release-3.6

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