Revert "feat: restrict some bot callbacks to maintainers-only"

[xtexx]

This reverts commit 8d2102c.

[MingcongBai]

For the record, this pull request is meant as a record correction:

• feat: support pipelines from fork PRs #43 allowed BuildIt! commands with forked PRs with authorized Telegram API (but not HTTP API).
• Implement user authorization #42 implements an authentication system and fix(security): reject new pipelines from unauthenticated HTTP API #44 authorized HTTP API.