Add Hlt2 and Sprucing event size qmtests

Those tests were removed when developing rate tests for Hlt2 and Sprucing in nightlies.

Now since the rate tests on nightlies don't run over lhcb-master-mr builds, it's necessary to ensure a MR doesn't crash those tests.

Both tests run on 100 events, and no limit is set on event sizes for now.

Requires LHCb!3700 (merged).

cc @nskidmor @abertoli