[IMP] crm: split results-oriented from perf-oriented assign tests

Purpose is to split assign tests related to results (leads being assigned,
with deduplication, compared to team and member domains) from tests related
to performance (query counters).

Assign process is a random process: randomizing teams leads to searching,
assigning and de-duplicating leads in various order. As a lot of search
are implied during assign process query counters may vary from run to run.
"Heavy" performance test included here ranged from 6K to 6.3K queries. Either
we set high counters maximum which makes those tests less useful. Either we
avoid random if possible which is what we decided to do by setting the seed
of random in tests.

SPECIFICATIONS

For results oriented tests remove query counters. Those tests should simply
ensure results of assign process, notably that even with random choice between
team and users we always have leads assigned with right domain and counts.

For performance oriented tests using query counters set random seed to have
a reproducible scenario and have less random in query counters.

LINKS

Task ID-2446759 (lead merge priority field management)
Task ID-2446883 (query counters fix)
PR odoo/odoo#65016