cmd/go: breaking change in 1.23rc2 with version constraints in GOPATH mode [1.23 backport]

[gopherbot]

@matloob requested issue #68658 to be considered for backport to the next 1.23 minor release.

@gopherbot please backport this to 1.23. It's necessary to unbreak GOPATH mode with certain build tags

[matloob]

cc @griesemer

[gopherbot]

Change https://go.dev/cl/608935 mentions this issue: [release-branch.go1.23] go/types, types2: use max(fileVersion, go1.21) if fileVersion present

[gopherbot]

Closed by merging CL 608935 (commit 7afe17b) to release-branch.go1.23.