Don't install Android NDK in CI

.github/workflows/android_builds.yml

@@ -6,7 +6,6 @@ env:
   GODOT_BASE_BRANCH: master
   SCONSFLAGS: platform=android verbose=yes warnings=extra werror=yes debug_symbols=no --jobs=2 module_text_server_fb_enabled=yes
   SCONS_CACHE_LIMIT: 4096
-  ANDROID_NDK_VERSION: 21.4.7075529
 
 jobs:
   android-template:
@@ -29,10 +28,6 @@ jobs:
         with:
           java-version: 8
 
-      - name: Install Android NDK
-        run: |
-          sudo ${ANDROID_HOME}/tools/bin/sdkmanager --install 'ndk;${{env.ANDROID_NDK_VERSION}}'
-
       # Upload cache on completion and check it out now
       - name: Load .scons_cache directory
         id: android-template-cache
@@ -64,7 +59,6 @@ jobs:
       - name: Compilation
         env:
           SCONS_CACHE: ${{github.workspace}}/.scons_cache/
-          ANDROID_NDK_ROOT: /usr/local/lib/android/sdk/ndk/${{env.ANDROID_NDK_VERSION}}/
         run: |
           scons target=release tools=no android_arch=armv7
           scons target=release tools=no android_arch=arm64v8