Use pytest-xdist or similar package for running tests in parallel

Migrated Jira Issue CDDSO-225
Jira creation date 06/12/2022 15:12

Some initial testing with [https://pytest-xdist.readthedocs.io/en/latest/|https://pytest-xdist.readthedocs.io/en/latest/|smart-link] has been quite promising, with tests taking roughly less than half the normal time whilst running on the VLD.

--> py.test -s cdds --doctest-modules .............    success! [841 passed, 81 deselected, 21 warnings in 15.36s]
--> py.test -s cdds -n auto --dist loadscope -m slow     success! [33 passed, 21 warnings in 141.98s (0:02:21)]
--> py.test -s cdds -n auto --dist loadscope -m integration     success! [2 passed, 4 warnings in 6.71s]
--> py.test -s cdds -n auto --dist loadscope -m data_request     success! [36 passed, 74 warnings in 34.49s]
Executing tests for mip_convert:
--> py.test -s mip_convert --doctest-modules -n auto     success! [712 passed, 23 warnings in 8.84s]
--> py.test -s mip_convert -m mappings -n auto ....    success! [57 passed, 8 warnings in 7.92s]
--> py.test -s mip_convert -m slow -n auto ........    success! [37 passed, 1 skipped, 762 warnings in 102.26s (0:01:42)]
++++++++++++++++++++++++++++++++++++++++++++++
Elapsed time: 0:05:21.822561
All tests succeed.
None 😄```

Need to modify ``command.extend(test.split(' ', 1))`` to ``command.extend(test.split(' '))`` in order to get extra options that are added to work correctly.
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Search the repository for command.extend(test.split(' ', 1)) and inspect how test commands and extra options are assembled. Update the argument handling so added options work correctly, then run the listed pytest commands and confirm that the test suites complete successfully.