Move ImageMutator after archMutator

Move the ImageMutator to be registered just after the archMutator
in preparation for moving it between osMutator and archMutator.
Requries updating variants in a few tests that now run the
ImageMutator.

Bug: 142286466
Test: no change to build.ninja
Test: all soong tests
Change-Id: Ia9d2a7bc0e225bedec3c9a83ea04f471a931bf47
diff --git a/xml/xml_test.go b/xml/xml_test.go
index 0a11566..f42ba77 100644
--- a/xml/xml_test.go
+++ b/xml/xml_test.go
@@ -104,7 +104,7 @@
 		{rule: "xmllint-minimal", input: "baz.xml"},
 	} {
 		t.Run(tc.schemaType, func(t *testing.T) {
-			rule := ctx.ModuleForTests(tc.input, "android_arm64_armv8-a").Rule(tc.rule)
+			rule := ctx.ModuleForTests(tc.input, "android_arm64_armv8-a_core").Rule(tc.rule)
 			assertEqual(t, "input", tc.input, rule.Input.String())
 			if tc.schemaType != "" {
 				assertEqual(t, "schema", tc.schema, rule.Args[tc.schemaType])
@@ -112,6 +112,6 @@
 		})
 	}
 
-	m := ctx.ModuleForTests("foo.xml", "android_arm64_armv8-a").Module().(*prebuiltEtcXml)
+	m := ctx.ModuleForTests("foo.xml", "android_arm64_armv8-a_core").Module().(*prebuiltEtcXml)
 	assertEqual(t, "installDir", buildDir+"/target/product/test_device/system/etc", m.InstallDirPath().String())
 }