Since OPMTaskified no longer opens the database on startup, collecting the metric of store initialization time should probably happen in the store.cc.

More context from the discussion:
fgorski@: The new model does not load the whole store in memory at startup, therefore this is not something we can measure.
We could measure the initialization of DB in general, or specific read operation instead, but this is impossible to measure in the new model.

carlosk@: Indeed! Let's then create a new metric to track only the store initialization time, without accounting for the 1st query (as that really doesn't make sense now that the 1st query can be anything). How about Model.InitializationTime?