fix: adapt permissions for certgen

[miltalex]

What type of PR is this?

What this PR does / why we need it:
This PR introduces a fix following the permissions changes in the build Dockerfile as part of the #5649

Which issue(s) this PR fixes:

Fixes #

Release Notes: No

[arkodg]

thanks for finding this @miltalex, can't figure out why CI was working fine these few weeks after the PR was merged

also I dont remember why 65534 was set for cert-gen so setting it 65532 and keep is consistent with the envoy-gateway deployment feels right

the third issue here is, do we need to rewrite the docker file so the User can be overwritten by k8s, I dont want to block this PR to tackle this issue though

[arkodg]

LGTM thanks !

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.26%. Comparing base (096cb8d) to head (c20f81c).
Report is 47 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5819      +/-   ##
==========================================
+ Coverage   65.19%   65.26%   +0.07%     
==========================================
  Files         214      219       +5     
  Lines       34321    34929     +608     
==========================================
+ Hits        22377    22798     +421     
- Misses      10591    10731     +140     
- Partials     1353     1400      +47     

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[miltalex]

thanks for finding this @miltalex, can't figure out why CI was working fine these few weeks after the PR was merged

also I dont remember why 65534 was set for cert-gen so setting it 65532 and keep is consistent with the envoy-gateway deployment feels right

the third issue here is, do we need to rewrite the docker file so the User can be overwritten by k8s, I dont want to block this PR to tackle this issue though

Thanks happy to tackle the third issue in a seperate PR

[arkodg]

@miltalex raised #5820 to tackle the third issue

[arkodg]

waiting on #5352 before merging this one to avoid conflicts