Rename flag IS_DOGFOOD to IS_STUDIO.

The flag is only set when building from Android Studio... and is never
used for dogfood.

Test: local
Change-Id: I898d585f4558c2437f0152ef102bea59c351f80b
diff --git a/src/com/android/launcher3/LauncherProvider.java b/src/com/android/launcher3/LauncherProvider.java
index 5544240..697048a 100644
--- a/src/com/android/launcher3/LauncherProvider.java
+++ b/src/com/android/launcher3/LauncherProvider.java
@@ -119,7 +119,7 @@
 
     @Override
     public boolean onCreate() {
-        if (FeatureFlags.IS_DOGFOOD_BUILD) {
+        if (FeatureFlags.IS_STUDIO_BUILD) {
             Log.d(TAG, "Launcher process started");
         }