chore: update Go to v1.27 (#39068)

Only made some necessary changes:

1. remove `GOEXPERIMENT`, only use jsonv2
1. `make fmt`
* `SigningKey` and `Signature` were affected due to some bugs in the
toolchain, so rewrote them
1. remove or fix fragile magic numbers and strings
    * the outputs of image/gzip/zlib packages are different
1. update "nolint" comments for the changed lint behaviors
1. add `tls.MLKEM1024`

services/convert/convert.go

@@ -169,7 +169,7 @@ func ToBranchProtection(ctx context.Context, bp *git_model.ProtectedBranch, repo
 	}
 
 	return &api.BranchProtection{
-		BranchName:                    branchName,
+		BranchName:                    branchName, //nolint:staticcheck // deprecated but useful to API response
 		RuleName:                      bp.RuleName,
 		Priority:                      bp.Priority,
 		EnablePush:                    bp.CanPush,