1PC can cause a window of inconsistency with L1 invalidation

The L1TxInterceptor currently doesn't block on L1 invalidations during a 1PC. This can cause an inconsistent view of data across non owner nodes.

Example:

Node A owns k with value of v1
Node B has k in L1 with value of v1

tx1 started
Node A put k -> v2
Node A sends invalidation
Node A commits
tx1 completed

tx2 started
Node B get k returns v1 from L1
tx2 completed

Node B gets invalidation for k

tx3 started
Node B get k remotely retrieves v2 from Node A
tx3 completed

We need to make sure that all L1 invalidations in Tx mode are completed before completing the transaction.