Revert^2 "Use the toolchain from JDK 17"

This reverts commit be3a561aac8ddc329dd89429b56b82690fd9a65d.

Reason for revert: Reland switch to JDK 17
Bug: 233029164
Test: TH

Change-Id: Ifa69e3fd50b853153a9c23756269ff12e72d7e9f
diff --git a/java/config/config.go b/java/config/config.go
index ea44aaa..a84c315 100644
--- a/java/config/config.go
+++ b/java/config/config.go
@@ -132,12 +132,7 @@
 		if override := ctx.Config().Getenv("OVERRIDE_JLINK_VERSION_NUMBER"); override != "" {
 			return override
 		}
-		switch ctx.Config().Getenv("EXPERIMENTAL_USE_OPENJDK17_TOOLCHAIN") {
-		case "true":
-			return "17"
-		default:
-			return "11"
-		}
+		return "17"
 	})
 
 	pctx.SourcePathVariable("JavaToolchain", "${JavaHome}/bin")
diff --git a/ui/build/config.go b/ui/build/config.go
index 14a99d0..15eea2d 100644
--- a/ui/build/config.go
+++ b/ui/build/config.go
@@ -387,13 +387,13 @@
 		if override, ok := ret.environ.Get("OVERRIDE_ANDROID_JAVA_HOME"); ok {
 			return override
 		}
-		if ret.environ.IsEnvTrue("EXPERIMENTAL_USE_OPENJDK17_TOOLCHAIN") {
-			return java17Home
-		}
 		if toolchain11, ok := ret.environ.Get("EXPERIMENTAL_USE_OPENJDK11_TOOLCHAIN"); ok && toolchain11 != "true" {
 			ctx.Fatalln("The environment variable EXPERIMENTAL_USE_OPENJDK11_TOOLCHAIN is no longer supported. An OpenJDK 11 toolchain is now the global default.")
 		}
-		return java11Home
+		if toolchain17, ok := ret.environ.Get("EXPERIMENTAL_USE_OPENJDK17_TOOLCHAIN"); ok && toolchain17 != "true" {
+			ctx.Fatalln("The environment variable EXPERIMENTAL_USE_OPENJDK17_TOOLCHAIN is no longer supported. An OpenJDK 17 toolchain is now the global default.")
+		}
+		return java17Home
 	}()
 	absJavaHome := absPath(ctx, javaHome)