gradle: use matching fallback instead of build type

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

tunnel/build.gradle.kts

@@ -50,9 +50,6 @@ android {
                 }
             }
         }
-        create("googleplay") {
-            initWith(getByName("release"))
-        }
     }
     lint {
         disable += "LongLogTag"

ui/build.gradle.kts

@@ -50,6 +50,7 @@ android {
         }
         create("googleplay") {
             initWith(getByName("release"))
+            matchingFallbacks += "release"
             buildConfigField("boolean", "IS_GOOGLE_PLAY", true.toString())
         }
     }