[7.17](backport #39472) updatecli: move to the .github folder and support for signed commits

[mergify]

Proposed commit message

updatecli: move to the .github folder and support for signed commits

To help with the migration from Jenkins so the .ci folder won't be needed for updatecli.
Use verified commits.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

Disruptive User Impact

Author's Checklist

• [ ]

How to test this PR locally

Related issues

Similarly done in elastic/apm-server#13107

Use cases

Screenshots

Logs

---

This is an automatic backport of pull request #39472 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 46de7e0 has failed:

On branch mergify/bp/7.17/pr-39472
Your branch is up to date with 'origin/7.17'.

You are currently cherry-picking commit 46de7e07de.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	deleted:    .ci/bump-elastic-stack-snapshot.yml
	renamed:    .ci/bump-golang.yml -> .github/workflows/updatecli.d/bump-golang.yml
	new file:   .github/workflows/updatecli.d/scm.yml

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   .github/workflows/bump-elastic-stack-snapshot.yml
	both modified:   .github/workflows/bump-golang.yml
	both modified:   .github/workflows/updatecli.d/bump-elastic-stack-snapshot.yml
	deleted by us:   .github/workflows/updatecli.d/bump-golang-7.17.yml

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[botelastic]

This pull request doesn't have a Team:<team> label.

[mergify]

This pull request has not been merged yet. Could you please review and merge it @v1v? 🙏