docs: update team management and contributor tracking documentation

[MohamedFazil1406]

Description

This PR replaces deprecated OpenSauced references in the maintainer documentation with GitHub-native alternatives.

Changes made

• Replaced OpenSauced Repository Insights and Contributor Insights references with GitHub Insights.
• Updated the "Identify New Talents" section to recommend GitHub Insights, Pull Requests, Issues, Discussions, and Contributor.info.
• Removed deprecated OpenSauced workflows and instructions that are no longer supported.
• Preserved the educational guidance for identifying and nurturing potential maintainers using currently available tools.

Related Issues

Fixes #272

Mobile & Desktop Screenshots/Recordings

Documentation only. No UI changes.

Steps to QA

1. Open docs/becoming-a-maintainer/your-team.md.
2. Verify that deprecated OpenSauced Repository Insight and Contributor Insight instructions have been removed.
3. Confirm the documentation recommends GitHub Insights, GitHub Teams, GitHub Actions, and Contributor.info where appropriate.
4. Open docs/becoming-a-maintainer/building-community.md.
5. Verify the "Identify New Talents" section references GitHub-native tools instead of OpenSauced features.
6. Ensure all removed OpenSauced references have been replaced with accurate, working alternatives.

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