Updated troubleshooting section for Deprecated Variable Usage

What does this MR do?

This merge request (MR) adds a troubleshooting section to address cases where a deprecated variable CI_BUILD_TOKEN is used instead of CI_JOB_TOKEN. The section will provide guidance on how to resolve issues related to the deprecated variable and avoid any potential problems that may arise from its usage.

Related issues

Author's checklist

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Reviewer's checklist

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