Bug 30465: Make BatchUpdateBiblio update the index in one request

Bug 30465: Make BatchUpdateBiblio update the index in one request

When using the batch record modification tool to modify several
bibliographic records, we don't want to send one index request per
biblio, we want to index them all on the fly after the records have been
modified.
Otherwise we will end up with one task per record, and records will be
indexed in background.

Test plan:
Use the batch mod tool to modify bibliographic records and confirm the
behaviour is correct.

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>