Refactor CI and libamambapy tests (on Unix) #805

Job	Run time
Unix tests (macos-latest, debug) / Build binaries	5m 21s
Unix tests (macos-latest, release) / Build binaries	3m 32s
Unix tests (ubuntu-latest, debug) / Build binaries	3m 49s
Unix tests (ubuntu-latest, release) / Build binaries	1m 55s
Unix tests (ubuntu-latest, release) / Test libmamba	1m 4s
Unix tests (ubuntu-latest, release) / Test integration micromamba	22m 26s
Unix tests (ubuntu-latest, release) / Test libmamba Python bindings	24s
Unix tests (macos-latest, release) / Test integration micromamba	44m 0s
Unix tests (macos-latest, release) / Test libmamba Python bindings	53s
Unix tests (macos-latest, release) / Test libmamba	2m 6s
Unix tests (ubuntu-latest, debug) / Test integration micromamba	31m 55s
Unix tests (ubuntu-latest, debug) / Test libmamba Python bindings	27s
Unix tests (ubuntu-latest, debug) / Test libmamba	1m 15s
Unix tests (macos-latest, debug) / Test libmamba Python bindings	1m 50s
Unix tests (macos-latest, debug) / Test libmamba	3m 4s
Unix tests (macos-latest, debug) / Test integration micromamba	40m 13s
	2h 44m 14s

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