Remove beta ecosystems feature flag for pre-commit

[AbhishekBhaskar]

What are you trying to accomplish?

This PR removes the check for enabling beta ecosystem enable_beta_ecosystems flag for pre-commit.

Anything you want to highlight for special attention from reviewers?

How will you know you've accomplished your goal?

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.

[Copilot]

Pull request overview

This PR removes the “beta ecosystems” gating for the pre-commit ecosystem so that fetching .pre-commit-config.* files is no longer blocked by the enable_beta_ecosystems / ALLOW_BETA_ECOSYSTEMS check.

Changes:

• Remove the beta-ecosystem guard and its “PreCommit support is currently in beta…” error from Dependabot::PreCommit::FileFetcher#fetch_files.
• Update the pre-commit file fetcher spec to stop registering the beta experiment and to remove the “beta disabled” failure-case coverage.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
pre_commit/lib/dependabot/pre_commit/file_fetcher.rb	Removes the beta feature-flag gate so file fetching proceeds unconditionally.
pre_commit/spec/dependabot/pre_commit/file_fetcher_spec.rb	Removes now-obsolete experiment setup and the spec asserting the beta-disabled error path.

[leuasseurfarrelds247-arch]

pre_commit/lib/dependabot/pre_commit/file_fetcher.rb