LP#1276222: apply correct TS maps when building field_entry index vectors

LP#1276222: apply correct TS maps when building field_entry index vectors

This patch ensures that only the approriate class- and field-level
TS maps get used when populating the index_vector column in
metabib.*_field_entry.  Prior to this patch, the active flag in each
config.metabib_*_ts_maps tables was ignored, meaning that one
could not disable a mapping without deleting it outright.  Furthermore,
defects in the query to fetch the TS maps to apply meant that *all*
ts_config in the class-level TS map table were used, not just
the ones that applied to the particular class.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>