ci(dependabot): remove config for GH mvn pkgs

[andrewazores]

Welcome to Cryostat3! 👋

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• Linked a relevant issue which this PR resolves
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To recreate commits with GPG signature git fetch upstream && git rebase --force --gpg-sign upstream/main

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Description of the change:

This change allows an environment variable to be configured so that...

Motivation for the change:

This change is helpful because users may want to...

How to manually test:

1. Run CRYOSTAT_IMAGE=quay.io... bash smoketest.bash...
2. ...

[github-actions]

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