chore: Removal of az.codesigning package since its been renamed

[Jaxelr]

Description

This PR deletes the az.codesigning module, since its been rebranded into az.trustedsigning on this PR #27332.

cc: @janielMartell

Mandatory Checklist

• Please choose the target release of Azure PowerShell. (⚠️Target release is a different concept from API readiness. Please click below links for details.)

  • General release
  • Public preview
  • Private preview
  • Engineering build
  • No need for a release

• Check this box to confirm: I have read the Submitting Changes section of CONTRIBUTING.md and reviewed the following information:

• SHOULD update ChangeLog.md file(s) appropriately
  • For SDK-based development mode, update src/{{SERVICE}}/{{SERVICE}}/ChangeLog.md.
    • A snippet outlining the change(s) made in the PR should be written under the ## Upcoming Release header in the past tense.
  • For autorest-based development mode, include the changelog in the PR description.
  • Should not change ChangeLog.md if no new release is required, such as fixing test case only.
• SHOULD regenerate markdown help files if there is cmdlet API change. Instruction
• SHOULD have proper test coverage for changes in pull request.
• SHOULD NOT adjust version of module manually in pull request

[azure-client-tools-bot-prd]

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[dolauli]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[dolauli]

@Jaxelr Please following the two PRs below to remove the module.
#27161
#27163

[Jaxelr]

@dolauli based on PR #27163, I removed the aforementioned files, except /tools/Tools.Common/SerializedCmdlets/Az.CodeSigning.json since it doesnt exist anymore.

[dolauli]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[dolauli]

LGTM