Add credentialsId to Git Parameter Plugin for authenticated branch/tag discovery

### What feature do you want to see added?

We use Git-based parameters in many Jenkins Pipelines (shared libraries, multibranch jobs) to let users select a branch/tag at build time. In our environment, these parameters often need to query private repositories/remotes where access depends on a specific Jenkins credential (different credentials per project/environment).

Previously this worked with list-git-branches-parameter-plugin because it allowed configuring an explicit credentialsId for branch/tag discovery. That plugin is no longer maintained, and we’re migrating to git-parameter-plugin, but it currently lacks a credentialsId option.

Request: please add an explicit credentialsId field to the Git Parameter definition and use it for remote operations when populating branches/tags/revisions. If not set, keep the current behavior for backward compatibility.

### Upstream changes

This would enable migration from the unmaintained plugin that previously supported explicit credentials selection:
https://github.com/jenkinsci/list-git-branches-parameter-plugin

### Are you interested in contributing this feature?

Not directly with code, but I can provide detailed logs, reproduction steps, and test builds in our Jenkins environment to validate the implementation.

No files or tests are named in the issue. Trace the Git Parameter definition and the remote operations used for branch, tag, and revision discovery, then inspect how Jenkins credentials are currently handled. Done means an explicit credentialsId is used when provided while existing behavior remains unchanged when it is absent.

Written by the indexing model from the issue text.