Optimize compilation of switch statements for untagged variants #5208

Job	Run time
build-rewatch (macos-13, x86_64-apple-darwin)	23s
build-compiler (ubuntu-latest, ocaml-variants.5.2.0+options,ocaml-option-static, true, true, true...	2m 40s
build-rewatch (macos-14, aarch64-apple-darwin)	15s
build-compiler (buildjet-2vcpu-ubuntu-2204-arm, ocaml-variants.5.2.0+options,ocaml-option-static,...	7m 19s
build-rewatch (ubuntu-latest, x86_64-unknown-linux-musl)	7s
build-compiler (macos-13, 5.2.0, true)	3m 51s
build-rewatch (buildjet-2vcpu-ubuntu-2204-arm, aarch64-unknown-linux-musl)	25s
build-compiler (macos-14, 5.2.0, true)	2m 8s
build-rewatch (windows-latest, x86_64-pc-windows-gnu)	24s
build-compiler (windows-latest, 5.2.0, true)	3m 6s
build-compiler (ubuntu-latest, ocaml-variants.5.0.0+options,ocaml-option-static)	1m 45s
build-compiler (ubuntu-latest, ocaml-variants.4.14.2+options,ocaml-option-static)	1m 36s
build-compiler (ubuntu-latest, ocaml-variants.4.13.0+options,ocaml-option-static)	1m 58s
package	27s
installationTest (macos-13)	22s
installationTest (macos-14)	21s
installationTest (ubuntu-latest)	16s
installationTest (buildjet-2vcpu-ubuntu-2204-arm)	29s
installationTest (windows-latest)	53s
publish	0s
	28m 45s

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