Remove obsolete build options from .bazelrc

This commit removes the following bazel options that were originally
added [1] to support bzlmod for Android (#1002).

 - experimental_enable_android_migration_apis
 - experimental_google_legacy_api

As far as we can see with Bazel 7.4.0, building Mozc with Bazel just
succeeds without the above two options in all the supported platforms.

This is a preparation to fully deprecate WORKSPACE support (#1115).

Closes #1117.

 [1]: 699c2ce

src/.bazelrc

@@ -75,8 +75,3 @@ build:windows_env --noincompatible_enable_cc_toolchain_resolution
 build:android_env --copt "-DOS_ANDROID"
 build:android_env --build_tag_filters=-noandroid
 test:android_env   --test_tag_filters=-noandroid
-
-## Android Blzmod specific options
-### --experimental_google_legacy_api is required for all platforms.
-build:bzlmod --experimental_google_legacy_api
-build:android_env --experimental_enable_android_migration_apis