Proposing: compacting lower and upper walls into a single file #3071

Job	Run time
codecheck / codecheck	45m 55s
conda / conda (ubuntu-20.04)	11m 0s
docker / docker (fedora39)	20m 50s
conda / conda (macos-12)	23m 10s
docker / docker (rocky8)	22m 54s
linux / linux (-doc-mpi-)	38m 21s
mac / macports (macos-12)	17m 17s
conda / conda (macos-14)	5m 9s
linux / linux (-mpi-)	50m 55s
linux / linux (-coverage-mpi-)	1h 2m 46s
mac / macports (macos-14)	8m 31s
mac / macsimple (macos-12)	8m 23s
mac / macports (+allmodules, macos-12)	26m 2s
linux / linux (-debug-)	32m 11s
mac / macsimple (macos-14)	4m 26s
linux / linux (-debug-mpi-)	41m 18s
linux / linux (-intel-)	44m 50s
linux / linux (-pycv-mpi-)	18m 22s
	8h 2m 20s

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