ci: Change the job name to make sense

[Yaminyam]

This pull request includes several changes to the .github/workflows/backport.yml file, primarily focusing on renaming the backport-target-branch to get-backport-target-branch in various sections of the workflow.

The most important changes include:

• Updated the if condition to use needs.get-backport-target-branch.outputs.matrix instead of needs.backport-target-branch.outputs.matrix.
• Changed the needs dependency from backport-target-branch to get-backport-target-branch.
• Modified the environment variables and commit message trailers to use get-backport-target-branch outputs instead of backport-target-branch outputs.
• Updated the author and PR details in the create-pull-request step to use get-backport-target-branch outputs.
• Adjusted the commit footer to reflect the new get-backport-target-branch naming convention.

Checklist: (if applicable)

• Milestone metadata specifying the target backport version

[Copilot]

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