Disable Valgrind for now #1755

Job	Run time
Check spelling using Typos	6s
ci gdal-3.10.0	2m 22s
ci ubuntu-lts	2m 24s
ci gdal-3.9.3	2m 21s
ci gdal-static (ubuntu-latest)	21m 47s
ci gdal-3.8.5	2m 14s
ci gdal-static (windows-latest)	23m 50s
ci gdal-3.7.3	2m 28s
ci gdal-static (macos-13)	58m 41s
ci gdal-3.6.4	2m 19s
ci gdal-static (macos-14)	27m 29s
ci gdal-3.5.3	2m 29s
ci gdal-3.4.3	2m 21s
	2h 30m 51s

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