Description

This PR changes the Applier to batch together DML statements into multi-statements in order to reduce the number of network trips in ApplyDMLEventQueries.

During testing on our --test-on-replica setup this provided around 10% increase in rows/second throughput

Rows Modified (rate); dml-batch-size=10

In case this PR introduced Go code changes:

• contributed code is using same conventions as original code
• script/cibuild returns with no formatting errors, build errors or unit test errors.