Mostly, scripts related to Bitcoin Core maintenance can be found in the bitcoin-maintainer-tools repository.
Some random other snippets:
- Start bitcoind in a screen in a debugger.
- Measure compilation speed as well as other statistics such as maximum memory usage per compilation unit. Original PR #6658.
- git-show-merge: show in which pull request a certain commit was merged into the current branch.
- blockdb-troubleshoot: collected bitcoin block database troubleshooting tools (from Python).
- bitcoin-submittx: stand-alone Bitcoin transaction submission tool (in Python).
- JSON-RPC batching example, there's also a functional test for batching.