TestValueFlow: Remove redundant test configuration, make settings const #1316

Job	Run time
build (ubsan, -DANALYZE_UNDEFINED=On, true, process, true)	2m 37s
build (tsan, -DANALYZE_THREAD=On, false, thread, false, --executor=thread --error-exitcode=0)	2m 11s
build (asan, -DANALYZE_ADDRESS=On, true, process, false)	2m 3s
	6m 51s

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