Clean up remaining config for rust gradle plugin submodule

.gitmodules

@@ -10,6 +10,3 @@
 [submodule "ios/wireguard-apple"]
 	path = ios/wireguard-apple
 	url = https://github.com/mullvad/wireguard-apple.git
-[submodule "android/rust-android-gradle-plugin"]
-	path = android/rust-android-gradle-plugin
-	url = https://github.com/mullvad/rust-android-gradle.git

android/config/config.mobsf

@@ -23,7 +23,3 @@
 
   # We've currently decided to support Android 9.
   - android_manifest_insecure_minsdk
-
-  # MobSFScan incorrectly reports that the targetSdk is less than 29 when it is not.
-  ignore-paths:
-  - "android/rust-android-gradle-plugin/sample/"

tombi.toml

@@ -1,6 +1,5 @@
 [files]
 exclude = [
-  "android/rust-android-gradle-plugin/**",
   "dist-assets/binaries/**",
   "ios/wireguard-apple/**",
   "windows/libwfp/**",