[gui][processing] Fix inconsistent behavior with the map layer widget's selected features only checkbox #36524

Job	Run time
build (24.04, 5, true, OFF, ON, ON, ON, ON, OFF, OFF, OFF, OFF, ON, false, ON)	33m 18s
build (39, 6, true, ON, OFF, ON, ON, OFF, OFF, ON, ON, ON, OFF, false, ON)	53m 54s
Run tests (5, ALL_BUT_PROVIDERS)	32m 33s
clang-tidy (24.04, 5)	4m 28s
Run tests (5, POSTGRES)	6m 34s
Run tests (5, HANA)	5m 45s
Run tests (6, ALL_BUT_PROVIDERS)	38m 43s
Run tests (5, ORACLE, 24.04, binary-for-oracle)	5m 49s
	3h 1m 4s

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