Merge "Switch to JDK 21" into main am: 092c3a56fb am: f30930f404

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2920125

Change-Id: I5e89bce53c531700ad958fb583b2594e4d9168f4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

java/config/config.go

@@ -132,12 +132,7 @@ func init() {
 		if override := ctx.Config().Getenv("OVERRIDE_JLINK_VERSION_NUMBER"); override != "" {
 			return override
 		}
-		switch ctx.Config().Getenv("EXPERIMENTAL_USE_OPENJDK21_TOOLCHAIN") {
-		case "true":
-			return "21"
-		default:
-			return "17"
-		}
+		return "21"
 	})
 
 	pctx.SourcePathVariable("JavaToolchain", "${JavaHome}/bin")