Skip disabled Maven repositories

[adoroszlai]

What are you trying to accomplish?

Skip Maven repositories which have both releases and snapshots disabled. Such repository definitions exist in pom.xml to avoid using them.

Fixes #15442

How will you know you've accomplished your goal?

Added a new custom repository in test fixtures with both releases and snapshots disabled. Tests are otherwise not modified, since the output is expected to be unchanged: the new repo should not appear in result of finder.repository_urls calls in existing test cases.

$ bin/docker-dev-shell maven
...
[dependabot-core-dev] ~ $ cd maven
[dependabot-core-dev] ~/maven $ rspec spec
...
726 examples, 0 failures

[dependabot-core-dev] ~/maven $ rubocop 
Inspecting 60 files
............................................................

60 files inspected, no offenses detected

Checklist

• I have run the complete test suite to ensure all tests and linters pass.
• I have thoroughly tested my code changes to ensure they work as expected, including adding additional tests for new functionality.
• I have written clear and descriptive commit messages.
• I have provided a detailed description of the changes in the pull request, including the problem it addresses, how it fixes the problem, and any relevant details about the implementation.
• I have ensured that the code is well-documented and easy to understand.