Clear holds shelf transaction can time out

Evergreen 2.2+

The API call "open-ils.circ.hold.clear_shelf.process" makes the misstep of creating a cstore transaction, then going off to make some unrelated, long-running API call. While waiting on the unrelated (to the cstore transaction) call to complete, the cstore transaction sometimes times out. To avoid this, the cstore transaction should not be started until the long-running call has completed and the work of actually updating data begins.

Ceci ne pas une patch! working => user/berick/clear-shelf-xact-timeout-repair