in conf_metadata_assign() enforcing that merge_range is always

in conf_metadata_assign() enforcing that merge_range is always
type_year _and_ enforcing that type_year is always range_merge, thus
setting contrains correctly at beginning of a server session setting
processing.
Removing these then unnecessary tests from ingest_record(), where
there will produce warnings logs nobody can do anything about at that
time, and where they are run for each ingested record.
Less code, less performed if statements, no unnecessary warning logs.