tests: Add hypothesis profile to run tests faster depending on location

Hypothesis allows different settings through profile. In our case, that would allows us to generate smaller samples on the ci.

This diff provides 2 profiles:

• dev: larger samples
• ci: lesser samples

That should be the other way around (largest on ci) but for now, that will do.

• [1] https://hypothesis.readthedocs.io/en/latest/settings.html#settings-profiles

Depends on !118 (closed)

Test Plan

• tox
• tox -e py3-slow
• make test (old way?)

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Migrated from D648 (view on Phabricator)