testHarness suite: recover integration with test metrics in the old system (coverage from test harness lost)

After re-implementing the test harness engine (PR #394) an issue has been found:

The old makefile target has been moved to an "old_" target:

```
old_functional_test: install_debug build_unit_test
	if [ -z "${BROKER_PORT}" ]; then \
	    echo "Execute '. scripts/testEnv.sh' before executing the tests"; \
	    exit 1; \
	fi
	make test -C BUILD_UNITTEST ARGS="-D ExperimentalTest" TEST_VERBOSE=1 || true
	@if [ -e test/testharness/*.diff ]; then \
           echo "A .diff file was found in test/testharness, which means that ctest failed running the test. This can happen if a \"Ok\""; \
           echo "token is used in the tests specification. Run \"scripts/testHarness.sh /test/testharness\" manually to find the problem."; \
	   exit 1; \
	fi
	@xsltproc scripts/cmake2junit.xsl BUILD_UNITTEST/Testing/`cat BUILD_UNITTEST/Testing/TAG| head -n1`/Test.xml  > BUILD_UNITTEST/functional_test.xml
```
The integration with test metrics (the make test and xslproc stuff) needs to be recovered in the new target.