six SA tests leave core files behind on macOS

The following six SA tests leave core files in /cores on macOS:

serviceability/sa/ClhsdbFindPC.java#id1
serviceability/sa/ClhsdbFindPC.java#id3
serviceability/sa/ClhsdbPmap.java#id1
serviceability/sa/ClhsdbPstack.java#id1
serviceability/sa/TestJmapCore.java
serviceability/sa/TestJmapCoreMetaspace.java

There is another SA test (serviceability/sa/ClhsdbCDSCore.java)
that generates core files, but it cleans up the core files after the
test is done:

$ grep coreFileName open/test/hotspot/jtreg/serviceability/sa/ClhsdbCDSCore.java
    private static String coreFileName;
                coreFileName = CoreUtils.getCoreFileLocation(crashOutput.getStdout());
            String useSharedSpacesOutput = test.runOnCore(coreFileName, cmds, null, null);
            test.runOnCore(coreFileName, cmds, expStrMap, unExpStrMap);
        if (coreFileName != null) remove(coreFileName);

The other SA tests should be updated to cleanup the core files.
Please note that this is only necessary on systems that put
the core files in a different directory than the test's execution
directory (macOS and some Linux configs).