Plan to split up test_other.py

[sbc100]

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.