all: enable alias type parameters GOEXPERIMENT by default

For #68778

Change-Id: I4b39f84665262251ca014d3f5fe74b2fd434d51e
Reviewed-on: https://go-review.googlesource.com/c/go/+/613236
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Commit-Queue: Tim King <taking@google.com>
Reviewed-by: David Chase <drchase@google.com>

src/internal/buildcfg/exp.go

@@ -71,6 +71,7 @@ func ParseGOEXPERIMENT(goos, goarch, goexp string) (*ExperimentFlags, error) {
 		RegabiWrappers:   regabiSupported,
 		RegabiArgs:       regabiSupported,
 		CoverageRedesign: true,
+		AliasTypeParams:  true,
 	}
 
 	// Start with the statically enabled set of experiments.

src/internal/goexperiment/flags.go

@@ -113,7 +113,7 @@ type Flags struct {
 
 	// AliasTypeParams enables type parameters for alias types.
 	// Requires that gotypesalias=1 is set with GODEBUG.
-	// This flag will be removed with Go 1.24.
+	// This flag will be removed with Go 1.25.
 	AliasTypeParams bool
 
 	// SwissMap enables the SwissTable-based map implementation.