Remove ndk download links up to r13b
Remove ndk download links up to r13b

JNI bridge will no longer be updated on Unity versions which use ndk <13

Unity-Technologies/android-jni-bridge,Unity-Technologies/android-jni-bridge,Unity-Technologies/android-jni-bridge,Unity-Technologies/android-jni-bridge,Unity-Technologies/android-jni-bridge,Unity-Technologies/android-jni-bridge