Plan to split up test_other.py

The test_other.py is rather unwieldy at 15k lines.

I already did an experiment where I split out all the js library tests into `test_jslib.py`.

My plan now is to split it up further, while somehow preserving a easy way to run the combined shares.

Proposed steps:

1. Split out a couple more chunks (e.g. `test_dylink.py`).
2. Rename the remaining test_other.py to test_misc.py (open to better suggestions on the name).
3. Make a alias such as that `./test/runner other` will run all the combined shards that used to be in test_other.py.

I already landed #26365 which means that all the tests from all the shards can be parallelized together.