Fix and test LinearFlowSolverLazyConstraint #859

Job	Run time
linters	30s
trigger	1s
build	13s
update-notebooks-for-colab-and-binder	2s
test (ubuntu-latest, 3.9)	31m 11s
test (ubuntu-latest, 3.12)	38m 55s
test (ubuntu-latest, 3.12, without gurobi)	29m 19s
test (macos-12, 3.9)	37m 11s
test (macos-latest, 3.12)	26m 42s
test (windows-latest, 3.9)	36m 11s
test (windows-latest, 3.12)	32m 41s
build-doc / build-doc	1m 25s
deploy	0s
deploy-doc	0s
	3h 54m 21s

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