We currently have a concept of `long_running` tests. If tests are flagged as `long_running` they will be skipped in PR testing, and if they are tagged as `extra_long_running` they will also be skipping in the merge queue.
WT-13201 will add a third category of `sanitizer_long` that only skipped when the tests run with (A|M|T|UB)San.

These concepts exist in both our Python tests and in our ctests. We should make sure our uses of each tag are consistent and add documentation to explain both the purpose of these tags and which tags are available.