Remove obsolete android ndk copy from //third_party/android_tools/ndk

It lives at //third_party/android_ndk

This is from chromium repo
https://chromium.googlesource.com/chromium/src/+/4d66cf2db5a7bfb68e089f4b10b87f06e2edd19c

Bug: None
Change-Id: Ia45355f1a7566a0b5268f7a3f33ca8e7dbe43451
Reviewed-on: https://webrtc-review.googlesource.com/c/107740
Reviewed-by: Oleh Prypin <oprypin@webrtc.org>
Commit-Queue: Oleh Prypin <oprypin@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25353}
diff --git a/DEPS b/DEPS
index 395dacc..4877c25 100644
--- a/DEPS
+++ b/DEPS
@@ -1393,8 +1393,6 @@
 recursedeps = [
   # buildtools provides clang_format, libc++, and libc++abi.
   'src/buildtools',
-  # android_tools manages the NDK.
-  'src/third_party/android_tools',
 ]
 
 # Define rules for which include paths are allowed in our source.