ci: Don't set `compiler-builtins-no-f16-f128` #2914

Job	Run time
build_system	27s
duplicates	4s
spell_check	9s
build (gcc-15.deb, --test-successful-rustc --nb-parts 2 --current-part 1)	16m 30s
build (gcc-15.deb, --extended-rand-tests)	8m 22s
build (gcc-15.deb, --extended-regex-tests)	11m 22s
build (gcc-15.deb, --extended-regex-example-tests)	6m 25s
build (gcc-15-without-int128.deb, --test-libcore)	17m 2s
build (gcc-15-without-int128.deb, --projects)	11m 20s
build (gcc-15-without-int128.deb, --test-successful-rustc --nb-parts 2 --current-part 1)	14m 1s
build (gcc-15.deb, --std-tests)	6m 44s
build (gcc-15-without-int128.deb, --test-successful-rustc --nb-parts 2 --current-part 0)	16m 35s
build (gcc-15.deb, --projects)	11m 15s
build (gcc-15.deb, --test-libcore)	16m 51s
build (gcc-15.deb, --test-successful-rustc --nb-parts 2 --current-part 0)	13m 24s
build (gcc-15-without-int128.deb, --extended-regex-tests)	12m 4s
build (gcc-15-without-int128.deb, --std-tests)	7m 28s
build (gcc-15-without-int128.deb, --extended-regex-example-tests)	7m 0s
build (gcc-15-without-int128.deb, --extended-rand-tests)	9m 8s
success	2s
	3h 6m 13s

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