Delete android example (bazelbuild#3954)

These examples have always been a big pain to maintain as they require
knowldge about the BuildKite runners (for NDK/SDK access) and there is
no active maintainer who has a ton of context in the Bazel+Android
world. While I think having the examples are nice, until the integration
is made more user friendly and we have a maintainer who can vouch for
it, I think they should be deleted.

Should the examples be reintroduced, they must be proven to work with
all active LTS versions of Bazel.

Author: UebelAndre

.bazelci/presubmit.yml

@@ -774,36 +774,6 @@ tasks:
     build_targets:
       - "@rust_toolchains//:all"
       - "//..."
-  android_examples_ubuntu2204:
-    name: Android Examples
-    platform: ubuntu2204
-    working_directory: examples/android
-    build_flags:
-      - "--incompatible_enable_android_toolchain_resolution"
-      - "--android_platforms=//:arm64-v8a"
-    build_targets:
-      - "//:android_app"
-    environment:
-      # This ndk version matches with rules_android_ndk repo's CI
-      # https://github.com/bazelbuild/rules_android_ndk/blob/877c68ef34c9f3353028bf490d269230c1990483/.bazelci/presubmit.yml#L37
-      # The ndk is installed by this script
-      # https://github.com/bazelbuild/continuous-integration/blob/ba56013373821feadd9f2eaa6b81eb19528795f0/macos/mac-android.sh
-      ANDROID_NDK_HOME: /opt/android-ndk-r25b
-  android_examples_macos:
-    name: Android Examples
-    platform: macos_arm64
-    working_directory: examples/android
-    build_flags:
-      - "--incompatible_enable_android_toolchain_resolution"
-      - "--android_platforms=//:arm64-v8a"
-    build_targets:
-      - "//:android_app"
-    environment:
-      # This ndk version matches with rules_android_ndk repo's CI
-      # https://github.com/bazelbuild/rules_android_ndk/blob/877c68ef34c9f3353028bf490d269230c1990483/.bazelci/presubmit.yml#L42
-      # The ndk is installed by this script
-      # https://github.com/bazelbuild/continuous-integration/blob/ba56013373821feadd9f2eaa6b81eb19528795f0/macos/mac-android.sh
-      ANDROID_NDK_HOME: /Users/buildkite/android-ndk-r25b
   ios_examples:
     name: iOS Examples
     platform: macos_arm64