We are building tests for collMod in op_applier_impl_test.cpp, and while this works for the cases where gFeatureFlagRequireTenantID=true, this doesn't currently work for gFeatureFlagRequireTenantID=false because the CollMod::parse() function builds the _dbName object first, then uses this to build the _nss object.  This means we don't benefit from the gFeatureFlagRequireTenantID-sensitive serializr/deserializer functions, and the tenantId remains prefixed onto the dbstring.

Either a change to how the collMod parser idl is defined is needed, or we need to add DatabaseName serializer/deserializer functions.  We should be able to use the existing collMod test as a template once this is complete.