Get cloud missions dynamically and fix cloud download workflow #5180

Job	Run time
egg_info with Python 3.9	18s
OSX, py310, all optional dependencies	3m 15s
Windows, py311, mandatory dependencies only	2m 39s
oldest version for all dependencies	1m 45s
Code style checks	24s
Linux ARM, py312, all optional dependencies	2m 6s
	10m 27s

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