Validate current channels length

[adriansmares]

Summary

References #5399
References https://the-things-industries.sentry.io/issues/4349395436

Changes

• Validate the length of the current channels in order to avoid panicing when too many current channels are generated.

Testing

Local testing.

Regressions

N/A. This fixes a corner case in the LinkADRReq generation that is a normal bounds check.

Checklist

• Scope: The referenced issue is addressed, there are no unrelated changes.
• Compatibility: The changes are backwards compatible with existing API, storage, configuration and CLI, according to the compatibility commitments in README.md for the chosen target branch.
• Documentation: Relevant documentation is added or updated.
• The steps/process to test this feature are clearly explained including testing for regressions.
• Changelog: Significant features, behavior changes, deprecations and fixes are added to CHANGELOG.md.
• Commits: Commit messages follow guidelines in CONTRIBUTING.md, there are no fixup commits left.