Remove test platform specification from release config (#20475)

PiperOrigin-RevId: 731061065

Author: mkruskal-google

.github/workflows/test_cpp.yml

@@ -52,6 +52,10 @@ jobs:
             cache_key: TcMalloc
             image: "us-docker.pkg.dev/protobuf-build/containers/test/linux/tcmalloc:7.1.2-d9624f2aa83cba3eaf906f751d75b36aacb9aa82"
             targets: "//src/... //third_party/utf8_range/..."
+          - config: { name: "aarch64", flags: "--platforms=//build_defs:aarch64_linux" }
+            cache_key: aarch64-bazel7
+            targets: "//src/... //src/google/protobuf/compiler:protoc_aarch64_test //third_party/utf8_range/..."
+            image: "us-docker.pkg.dev/protobuf-build/containers/test/linux/emulation:7.1.2-aarch64-2920199ab0090ed427413a8e422e62695c8392a8"
     name: ${{ matrix.config.continuous-only && inputs.continuous-prefix || '' }} Linux ${{ matrix.config.name }}
     runs-on: ${{ matrix.config.runner || 'ubuntu-latest' }}
     steps:

toolchain/toolchains.bazelrc

@@ -3,9 +3,8 @@ build:cross_config --//toolchain:release=true
 build:cross_config --host_crosstool_top=@bazel_tools//tools/cpp:toolchain
 build:cross_config --incompatible_enable_cc_toolchain_resolution=false
 
-# Set platform explicitly for aarch64 emulation images.
-build:linux-aarch_64 --config=cross_config --cpu=linux-aarch_64 --platforms=//build_defs:aarch64_linux
-build:linux-aarch64 --config=cross_config --cpu=linux-aarch_64 --platforms=//build_defs:aarch64_linux
+build:linux-aarch_64 --config=cross_config --cpu=linux-aarch_64
+build:linux-aarch64 --config=cross_config --cpu=linux-aarch_64
 build:linux-ppcle_64 --config=cross_config --cpu=linux-ppcle_64
 build:linux-ppc64le --config=cross_config --cpu=linux-ppcle_64
 build:linux-s390_64 --config=cross_config --cpu=linux-s390_64