Merge in CASA/casa6 from CAS-13359 to master
* commit '5c33a81582dbdaa21dea29ccb23df972dbfae96c':
Now usescratch's default is True in setjy, modified setjy command in test_model_keys to explicitly set usescatch=False
Add a test for the exception handling
Modify to use RuntimeError rather than generic Exception and the boolean comparison to follow PEP8
Minor edit to retrigger build
A minor edit in the xml help doc
Change the default for usescratch to True. Catch to raise an exception when Butler-JPL-Horizons and usescratch = False are set.