Add some stability to the eviction policy NDFs

MINOR MERGE REQUEST

Overview

Was able to reproduce the NDF locally, usually within 10 iterations. Refactored the test checks into a consistent helper function. Added a helper log function as well in case it comes back. Was able to run it locally over 50 times without a failure.

Fixes include:

1. tg.Sync() calls after rapid mining
2. All txns checks in build.Retry
3. Occasional mining when checking for evictions.

Issues Closed