SERVER-101591 broke things for the case where execution continues after saveState() throws a WriteConflictException, but none of the tests in the required build variants caught this problem. "jstestfuzz_concurrent_replication_write_conflicts" caught the problem (see BF-37007), but "jstestfuzz_concurrent_replication_write_conflicts" is a non-deterministic fuzzer-style test that doesn't run in any of the required build variants.

Unfortunately, it seems like we lack any deterministic non-fuzzer tests that would catch this problem.

As part of this ticket, we should:

• Make unit tests for PlanYieldPolicy
• Add more unit tests to cover scenarios where we call saveState()/restoreState() on SBE plan stage trees
• Add unit tests that cover the case where execution continues after saveState() throws a WriteConflict exception
• Verify that these new unit tests would have caught the bug introduced by SERVER-101591