LOCK_MAX_N_STEPS_IN_DEADLOCK_CHECK, LOCK_MAX_DEPTH_IN_DEADLOCK_CHECK,
LOCK_RELEASE_INTERVAL: Replace with the bare use of the constants.

lock_rec_create_low(): Remove LOCK_PAGE_BITMAP_MARGIN altogether.
We already have REDZONE_SIZE as a 'safety margin' in AddressSanitizer
builds, to catch any out-of-bounds access.

lock_prdt_add_to_queue(): Avoid a useless search when enqueueing
a waiting lock request.

lock_prdt_lock(): Reduce the size of the trx->mutex critical section.