Revert "app: enable split apk builds"

Not compatible with F-Droid.

If you can fix F-Droid builds, send pull requests. For now I'm disabling this.

This reverts commit a7eb173178.

app/build.gradle

@@ -25,14 +25,9 @@ android {
                 cFlags "-std=c11", "-Wall", "-Wextra", "-Werror", "-Os", "-fno-stack-protector", "-Wl,--gc-sections"
             }
         }
-    }
 
-    splits {
-        abi {
-            enable true
-
-            reset ()
-            include 'x86', 'x86_64', 'armeabi-v7a', 'arm64-v8a'
+        ndk {
+            abiFilters 'x86', 'x86_64', 'armeabi-v7a', 'arm64-v8a'
         }
 
     }