Implement performance regression testing

Ensures that tests run in an acceptable amount of time.
Needs at least 5 runs. Can cause failures of test-only due to
warm-up and class loading effects.
Add synthesis regression test suite

For now only synthesis tests that 100% pass. The rest of benchmarks need
to be investigated due to memory consumption issues
Remove TestUtils, don't look in innexistent directories
Timeout tests that take too long, just in case