TestTxn_Apply_LockDelay

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#### Overview of the Issue

`TestTxn_Apply_LockDelay` can fail in CI. Ran this on my local machine 2000 times without much else running and observed 0 failures. Will likely only occur under high resource contention. Have not triaged the exact cause, but I expect it's timing based.

https://github.com/hashicorp/consul/blob/5934f803bfb54c1ceeeb6518398f1b82a726459f/agent/consul/txn_endpoint_test.go#L616

#### Reproduction Steps

Run this test in a resource constrained env such as CI or `make test-flake`

### Operating system and Environment details

CircleCI

### Log Fragments

CI Logs: https://circleci.com/gh/hashicorp/consul/57870#tests/containers/1