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.
We don't need this part any longer, as it is "embedded" in the coverage and coverage_functiona_test targets.

NTC