testsuite: rename some test scripts * tests/parallel-tests-am_tests_environment.test: Renamed ... * tests/am-tests-environment.test: ... to this. * tests/check-tests_environment.test: Renamed ... * tests/tests-environment.test: ... to this. * tests/parallel-test-driver-install.test: Renamed ... * tests/parallel-tests-driver-install.test: ... to this. * tests/parallel-tests-make-n.test: Renamed ... * tests/parallel-tests-dry-run.test: ... to this. * tests/Makefile.am (TESTS): Updated.