Bug 35648: (follow-up) Clear table filter before submitting

Bug 35648: (follow-up) Clear table filter before submitting

This patch takes advise from elasticsearch-mappings.js and adds an
onsubmit event to clear any DataTables filter before submitting. This
should prevent hidden fields from being overwritten.

To test, filter the table and make a change to one of the visible rows.
After submitting, confirm that the previously-hidden rows retain the
same settings as before.

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>