Bug 38416: Failover to MARCXML if cannot roundtrip USMARC during indexing

Bug 38416: Failover to MARCXML if cannot roundtrip USMARC during indexing

This change failsover to MARCXML from USMARC if there are any
warnings generated by MARC::File::USMARC::decode when trying to
roundtrip the record.

Test plan:
0. Apply the patch
1. Setup your koha-testing-docker to use Elasticsearch
2. Create a new record with 15,000 characters in the 500$a field
3. Index that record
(e.g. perl misc/search_tools/rebuild_elasticsearch.pl --biblios -v -v)
4. Note that a warning saying the following appears:
"Warnings encountered while roundtripping a MARC record to/from USMARC.
Failing over to MARCXML"
5. View the "Elasticsearch record" on the detail page and note that the
marc_format is MARCXML
6. Perform a search for the record (the keyword should be something that
brings up other results too)
7. Note that the record appears correctly in the search results

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>