In SERVER-101589 we added more tests to the suites but we needed to force a larger `exec_timeout_secs` for the suite because the auto calculated one (300 secs) was too shorts. In fact, the jstests/sharding/mongos_writes_wait_for_write_concern_timeseries.js usually runs longer than 300 secs.

The goal of the ticket is to remove the forced timeout and see if the automatic one have been adjusted to the long runtime of the problematic test.