Perf: improve sync GitHub speed

[Yuxiang-Huang]

Using ThreadPoolExecutor on teams similar to
[https://github.com/ScottyLabs/governance/commit/cbc1bfe382459f9c007e0198574548b89c478892],
need to change logging by grouping all logs of a team into a canonical log.
Otherwise the logs gets interleaved together.

For testing, uv run sync --services github.
Try using your own GitHub token, which should allow you to read the teams after you join ScottyLabs.
Otherwise, ask in Slack for a GitHub token with read permission to ScottyLabs teams.

Acceptance criteria: screenshots of timed GitHub sync runs that shows significant improvement