PYTHON-4902 Use shrub.py to generate tasks

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Before: 1538 tasks across 194 build variants
After: 2285 tasks across 131 build variants

Ensures a consistent set of tests available for all python and server versions with the following combo:

SUB_TASKS = [
    ".sharded_cluster .auth .ssl",
    ".replica_set .noauth .ssl",
    ".standalone .noauth .nossl",
]

The full set of auth/ssl and topology is only tested on RHEL for the three main python versions.
We split up the tasks on RHEL8 into async/sync as well, which accounts for a lot of the extra tasks, but the overall runtime will be similar.

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I'll adjust the GitHub PR tasks to only run that subset on PRs after we merge.