Improve isolated process error handling

[andre15silva]

The current error logging of OOM errors from the isolated test running process is not great, and can result in misleading errors such as java.lang.RuntimeException: java.nio.file.NoSuchFileException: CoveredTestResultPerTest.dat (ASSERT-KTH/flacoco#121)

For that we probably need to change the way we check if the process exited successfully here:

test-runner/src/main/java/eu/stamp_project/testrunner/EntryPoint.java

Lines 760 to 767 in 6130e56

	long startTime = System.currentTimeMillis();
	boolean finished = process.waitFor(timeoutInMs, TimeUnit.MILLISECONDS);
	long endTime = System.currentTimeMillis();
	if (!finished) {
	throw new RuntimeException("Forked process did not finish correctly. " +
	"Timeout set was " + timeoutInMs + " ms, " +
	"process took " + (endTime - startTime) + " ms before ending.");
	}