CI: fix kcfg sync workflow

[tao12345666333]

What this PR does / why we need it:

This pull request includes updates to the GitHub Actions workflow for syncing Kubernetes configuration CRDs. The changes focus on updating permissions, switching the shell used for a script, and modifying the process for committing changes to a new branch.

Workflow updates:

• .github/workflows/sync-kubernetes-configuration-crds.yaml: Added permissions section to grant write access to contents.
• .github/workflows/sync-kubernetes-configuration-crds.yaml: Changed the shell used for the Kustomize installation script from sh to bash.
• .github/workflows/sync-kubernetes-configuration-crds.yaml: Replaced the action for creating a pull request with an action to push changes to a new branch, including updating commit message and branch creation options.

Which issue this PR fixes

(optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged)

• fixes #

Special notes for your reviewer:

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• PR is based off the current tip of the main branch.
• Changes are documented under the "Unreleased" header in CHANGELOG.md
• New or modified sections of values.yaml are documented in the README.md
• Commits follow the Kong commit message guidelines

[tao12345666333]

Since our current security policy does not allow creating PRs via GitHub actions, I will modify its goal to only prepare branches via CI and then create PRs manually.

[tao12345666333]

An example of a successful GitHub action that I ran using this configuration

https://github.com/Kong/charts/actions/runs/13559914224/job/37901027452

It created such a commit

3981515

[pmalek]

Since our current security policy does not allow creating PRs via GitHub actions, I will modify its goal to only prepare branches via CI and then create PRs manually.

AFAIK this limitation is only for GITHUB_TOKEN, right? If we'd use a custom PAT then we could create the PRs (given that the permission for this would be assigned to the PAT). WDYT?

[tao12345666333]

Yes.

However, there is no bot token set in this repository. Maybe we can set some secrets like in kic repo.

[tao12345666333]

The workflow has been fixed through this PR, and it has run successfully.
https://github.com/Kong/charts/actions/runs/13567191027

It created a PR.
#1259

[tao12345666333]

Using the latest update, it has run successfully and created this PR.

[pmalek]

Just 2 minor nits, otherwise LGTM.

Please also resolve the conflicts.

[tao12345666333]

Created #1276

[pmalek]

I believe this PR missed setting the .version and .appVersion in the chart. #1278 attempts to do just that.

@tao12345666333 PTAL

[tao12345666333]

thank you!