Replaced filter_desc with dynamic label checking

[kubajal]

This PR:

1. replaces filter_desc functionality with checking matching test labels in the runtime by comparing the selectors with current stack maintained by local_description_push
2. Also, instead of checking for string-string equality, it checks for string-regex matching; this gives more flexibility in selecting subsets of tests

Fixes #2222

To do: increase test coverage and fix snapshot failures (I don't know how to do that).

[hadley]

As I mentioned in the issue, I don't think this is a good idea, sorry.