Skip Gradle cooldown metadata fetch when cooldown is not configured

[yeikel]

What are you trying to accomplish?

Avoids unnecessary network requests to fetch release-date metadata on every Gradle job when the user has no cooldown configured (the default).

Fixes #14152

Anything you want to highlight for special attention from reviewers?

As described in #14152, fetching this metadata by default when cooldown is not configured is wasteful

How will you know you've accomplished your goal?

• Both existing and new tests pass

CLI tests:

Reproducer: https://github.com/yeikel/dependabot-reproducer-issue-15136

1. The metadata is not fetched when cooldown is not configured

Before:

After:

2. The metatadata continues to to be fetched when cooldown is configured

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.