Bug 18329 - Batch record deletion broken

Bug 18329 - Batch record deletion broken

Hie, Tools > Batch record deletion seems broken.
Any deletion returns error :
Bibliographic record YYY was not deleted. An error occurred. (The error was: {UNKNOWN}: DBD::mysql::db begin_work failed: Already in a transaction at /usr/share/perl5/DBIx/Class/Storage/DBI.pm line 1560. at /home/koha/src/C4/Biblio.pm line 3468 , see the Koha log file for more information).

Looks like it is because of Bug 18242 which added a transaction  in C4::Biblio::_koha_delete_biblio_metadata : $schema->txn_do.
The script batch_delete_records created a transaction with $dbh->{AutoCommit} = 0;

This patch fixes by using also Koha::Schema in batch_delete_records to manage transaction.
It also removes "$dbh->{RaiseError} = 1", this behavior is managed in Koha::Database.

Test plan :
 - Go to Staff interface : Tools > Batch record deletion
 - Enter a few existing biblionumbers
 - Click on "Continue"
 - Click on "Delete selected records"
=> Without patch you get a DB error
=> With patch you get confirmation message
 - Try to get the biblios to confirm they are deleted : /cgi-bin/koha/catalogue/detail.pl?biblionumber=xxx
 - Test with and without Plack

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Mason James <mtj@kohaaloha.com>