Delete ApiBp2build soong_build mode

This feature is obsolete.

This makes a large number of codepaths "dead code" (such as
module-specific implementations of ApiBp2build functionality). These
will be deleted in a followup CL.

Bug: 284029211
Test: Presubmits
Change-Id: Ib53b99f1fe8c24380d219caf44e9bb3b96724fa0

tests/bp2build_bazel_test.sh

@@ -407,38 +407,6 @@ EOF
   fi
 }
 
-# Smoke test to verify api_bp2build worksapce does not contain any errors
-function test_api_bp2build_empty_build() {
-  setup
-  run_soong api_bp2build
-  run_bazel build --config=android --config=api_bp2build //:empty
-}
-
-# Verify that an *_api_contribution target can refer to an api file from
-# another Bazel package.
-function test_api_export_from_another_bazel_package() {
-  setup
-  # Parent dir Android.bp
-  mkdir -p foo
-  cat > foo/Android.bp << 'EOF'
-cc_library {
-  name: "libfoo",
-  stubs: {
-    symbol_file: "api/libfoo.map.txt",
-  },
-}
-EOF
-  # Child dir Android.bp
-  mkdir -p foo/api
-  cat > foo/api/Android.bp << 'EOF'
-package{}
-EOF
-  touch foo/api/libfoo.map.txt
-  # Run test
-  run_soong api_bp2build
-  run_bazel build --config=android --config=api_bp2build //foo:libfoo.contribution
-}
-
 function test_bazel_standalone_output_paths_contain_product_name {
   setup
   mkdir -p a