Remove code owner @rt4914 from all non-xml files (oppia#4875)

Remove code owner @rt4914 from all non-xml files

.github/CODEOWNERS

@@ -63,7 +63,7 @@ gradlew.bat @BenHenning
 *.pro @BenHenning
 
 # Lesson assets.
-/domain/src/main/assets/ @BenHenning @rt4914
+/domain/src/main/assets/ @BenHenning
 
 # Android manifests and top-level app configuration.
 *Manifest.xml @BenHenning
@@ -106,8 +106,8 @@ config/kitkat_main_dex_class_list.txt @BenHenning
 #####################################################################################
 
 # Global app module code ownership.
-/app/**/*.kt @BenHenning @rt4914
-/app/**/*.java @BenHenning @rt4914
+/app/**/*.kt @BenHenning
+/app/**/*.java @BenHenning
 
 # State players.
 /app/src/*/java/org/oppia/android/app/player/ @BenHenning
@@ -183,13 +183,13 @@ config/kitkat_main_dex_class_list.txt @BenHenning
 /utility/src/test/res/values/strings.xml @BenHenning
 
 # Accessibility utilities.
-/utility/src/*/java/org/oppia/android/util/accessibility/ @BenHenning @rt4914
+/utility/src/*/java/org/oppia/android/util/accessibility/ @BenHenning
 
 # Core logging infrastructure.
 /utility/src/*/java/org/oppia/android/util/logging/ @BenHenning
 
 # Miscellaneous statusbar UI utilities.
-/utility/src/*/java/org/oppia/android/util/statusbar/ @BenHenning @rt4914
+/utility/src/*/java/org/oppia/android/util/statusbar/ @BenHenning
 
 #####################################################################################
 #                                     scripts                                       #