chore: leave the validation of setHeaderRoute to the plugin when plug…

[denis-codefresh]

…ins is not empty. (argoproj#2898)

chore: leave the validation of setHeaderRoute to the plugin if plugins not empty.

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this is a chore.
• The title of the PR is (a) conventional with a list of types and scopes found here, (b) states what changed, and (c) suffixes the related issues number. E.g. "fix(controller): Updates such and such. Fixes #1234".
• I've signed my commits with DCO
• I have written unit and/or e2e tests for my change. PRs without these are unlikely to be merged.
• My builds are green. Try syncing with master if they are not.
• My organization is added to USERS.md.

[github-actions]

Go Published Test Results

2 068 tests   2 068 ✅  2m 47s ⏱️
  118 suites      0 💤
    1 files        0 ❌

Results for commit 594f87a.

♻️ This comment has been updated with latest results.

[github-actions]

E2E Tests Published Test Results

  4 files    4 suites   3h 23m 20s ⏱️
103 tests  93 ✅  6 💤 4 ❌
416 runs  388 ✅ 24 💤 4 ❌

For more details on these failures, see this check.

Results for commit 594f87a.