[GBA-7] Fix rerun comment flow and add test for invalid PullRequestCommit

[RodrigoMNardi]

• Improved the rerun flow triggered by comments, ensuring correct handling when the PullRequestCommit is invalid.
• Added a new test scenario to cover cases where Github::Parsers::PullRequestCommit#invalid? returns true, ensuring the system responds with an error and adds a reaction to the comment.
• Fixed potential issues with duplicate primary keys in test factories by letting ActiveRecord handle IDs automatically.
• Enhanced test coverage for edge cases involving multiple PRs and check suites.