Golang cmd/go: crash on unknown GOEXPERIMENT during toolchain selection [1.24 backport]

@prattmic requested issue #74111 to be considered for backport to the next 1.24 minor release.

@gopherbot Please backport to 1.24. This is a regression in passing GOEXPERIMENT to another version selected via GOTOOLCHAIN.

Comment From: gopherbot

Change https://go.dev/cl/682735 mentions this issue: [release-branch.go1.24] cmd/go/internal/fips140: ignore GOEXPERIMENT on error

Comment From: gopherbot

Closed by merging CL 682735 (commit e03869084788ed039f04336d9d8f7e9fa43c534e) to release-branch.go1.24.