Add unified-domain to solve porous flow #9021

Job	Run time
pydocstyle	10s
Mypy	3m 39s
Pylint	3m 57s
Flake8	18s
Pytest	2h 28m 18s
Documentation	4m 43s
Examples (ubuntu-latest)	1h 2m 35s
Emirge installation (ubuntu-latest)	5m 0s
Examples (porter)	1h 26m 27s
Production testing (ubuntu-latest)	57m 29s
Emirge installation (macos-latest)	8m 55s
Production testing (macos-latest)	49m 28s
Production testing (porter)	1h 6m 7s
	8h 17m 6s

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