BUG-865: TransactionCommitDeadlockException safety

This patch fixes safety (public non-constant field) and improves
performance by using a shared RpcError instances. Also moves over to use
a Supplier instead of a Function.

Change-Id: Id9d269fe9be6dacea3c216d4ad76efa79bdb27f0
Signed-off-by: Robert Varga <rovarga@cisco.com>