Accessing private maven repo using default GitHub configuration

**Description of the issue**

We've been using the advanced configuration option for GitHub for awhile now with no issues. With all of the improvements made to the default configuration option, I wanted to experiment with it to simplify management of our CodeQL configuration. I switched from advanced to default and created a branch that eliminated our CodeQL workflow and configuration file to test it out.

The default CodeQL check triggered and appears to have scanned the code successfully. However, when I view the results under `Security | Code scanning | Tools | CodeQL (Default setup) | View configuration`, warnings appear that CodeQL was unable to extract dependency information from gradle.


After further investigation this appears to be caused by the fact that our project uses a private maven repo for retrieving dependencies and the CodeQL workflow does not have access to these credentials. Is there a way to fix this or is my only option to stick with the advanced configuration? If the latter, any chance support for this might be added?

Start by investigating the default CodeQL setup's Gradle dependency extraction with a project that uses a private Maven repository, then review how credentials are made available to that workflow. Done means dependency information is extracted successfully with private-repository credentials, or the supported limitation and workaround are documented.

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