Comment out non-implemented variant #15824

Job	Run time
regression (macos-latest, ocaml-variants.4.14.2+options,ocaml-option-flambda)	17m 23s
regression (ubuntu-latest, ocaml-variants.4.14.2+options,ocaml-option-flambda)	7m 29s
extraction	-1s
	24m 51s

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