[CI][precommit] Fix instruction command in validate helm hook

[LeoLiao123]

Why are these changes needed?

If following the original instructions in scripts/validate-helm.sh, cannot correctly execute the generate-crd-schema hook.

Related issue number

None

Manual test

Checks

• [x] I've made sure the tests are passing.
• Testing Strategy
  • [ ] Unit tests
  • [x] Manual tests
  • [ ] This PR is not tested :(