Fix reproducible "no transaction to rollback" when loading bookbag.

Fix reproducible "no transaction to rollback" when loading bookbag.

Remove most transaction code from load_myopac_bookbags in OpenILS::WWW::
EGCatLoader::Account, only doing xact_begin when an update is called for.

It looks like the original transaction may have been created to prevent
the bookbags from changing while being loaded.  The comment on the line
where the xact_begin call originally was simply said 'replication...'
I don't know what problem, if any, that transaction was created to resolve,
but dropping most of the transaction code from that method does resolve a
reproducible bug.

(I also don't know exactly what in the patron's bookbags caused the no
transaction to rollback error, but it always appears with the same bookbag
with regularity.)

Signed-off-by: Jason Stephenson <jason@sigio.com>