Remove SortedStringKeys

We have SortedKeys instead now.

Test: Presubmits
Change-Id: I27b38c63cdd770d6bef70e08ae38fdddc066c0f8
diff --git a/android/plugin.go b/android/plugin.go
index d62fc94..4348f14 100644
--- a/android/plugin.go
+++ b/android/plugin.go
@@ -135,6 +135,6 @@
 		disallowedPlugins[name] = true
 	})
 	if len(disallowedPlugins) > 0 {
-		ctx.Errorf("New plugins are not supported; however %q were found. Please reach out to the build team or use BUILD_BROKEN_PLUGIN_VALIDATION (see Changes.md for more info).", SortedStringKeys(disallowedPlugins))
+		ctx.Errorf("New plugins are not supported; however %q were found. Please reach out to the build team or use BUILD_BROKEN_PLUGIN_VALIDATION (see Changes.md for more info).", SortedKeys(disallowedPlugins))
 	}
 }