add startupProbe validation

[thiagomedina]

Fixes #16256

Proposed Changes

• Add startup probe validation in validateUserContainer and validateSidecarContainer
• Update existing tests that included startup probes but had no expected errors since the validation was missing

Release Note

 Add validation for startup probes in user and sidecar containers 

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.20%. Comparing base (06f2ba7) to head (9fcd924).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16594      +/-   ##
==========================================
- Coverage   80.21%   80.20%   -0.01%     
==========================================
  Files         217      217              
  Lines       13545    13550       +5     
==========================================
+ Hits        10865    10868       +3     
  Misses       2316     2316              
- Partials      364      366       +2     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[dprotaso]

Just need to run this tool on the file change

https://github.com/mvdan/gofumpt

[dprotaso]

Mind filling out the release note section in your PR body?

/lgtm
/approve

thanks for the change

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dprotaso, thiagomedina

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• pkg/apis/OWNERS [dprotaso]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[thiagomedina]

Mind filling out the release note section in your PR body?

sure, thanks