Speed up LocalFile locking behavior

* Lowered the lock() timeout
* Wrap the destination DB write with memcached locks for move
  ops since it is easier to control that lock timeout than the
  DB lock timeouts.
* Cleanup locks in the destructor (e.g. on exceptions). Other
  process can pile up more if locks have to expire.

bug: 63058
Change-Id: I38b28d81ec96daa80ece2354db284a614289ba0b