race analysis fails for several tests on Amazon Linux

This test deadlocks under race detection, but only on Linux:

```bash
go test -race -test.run="TestPgIndex" -timeout=1m ./...
```

The enginetests fail race analysis, but only on Linux (not Mac or Windows):

```bash
go test -race $(go list ./testing/go/enginetest)
```

This surely has something to do with running multiple Dolt servers in the same process, which they were never designed to do, but it's not clear why this is a Linux-only problem (maybe an Amazon-Linux-only problem) or why essentially the same approach fails in the enginetest package but not in the other tests, which also start servers.