Disable Vulkan driver in macOS runtime packages. (iree-org#18324)

Rather than use custom logic in the release package build, this falls
back to using the base CMake logic that disables Vulkan in favor of
Metal on Apple platforms:
https://github.com/iree-org/iree/blob/8e42839893f40788357e38b2856ca5930cb4b47b/CMakeLists.txt#L267-L272

This should fix the `macos :: Build py-runtime-pkg` nightly release
build, which started failing a few weeks ago
* Latest failing logs:
https://github.com/iree-org/iree/actions/runs/10506137072/job/29105159765

    ```
ld: building fixups: pointer not aligned at
__ZN4iree3hal6vulkan12_GLOBAL__N_124kDynamicFunctionPtrInfosE+0xC from
/tmp/lto.o
clang: error: linker command failed with exit code 1 (use -v to see
invocation)
    ```

* Test logs with this PR on my fork:
https://github.com/ScottTodd/iree/actions/runs/10513089016/job/29127873585

build_tools/python_deploy/build_macos_packages.sh

@@ -72,9 +72,7 @@ function run() {
 }
 
 function build_iree_runtime() {
-  # TODO(antiagainst): remove Vulkan once IREE_HAL_DRIVER_METAL is stable
   export IREE_RUNTIME_BUILD_TRACY=ON
-  IREE_HAL_DRIVER_VULKAN=ON \
   python3 -m pip wheel -v -w $output_dir $repo_root/runtime/
 }
 

runtime/setup.py

@@ -275,10 +275,6 @@ def build_configuration(cmake_build_dir, cmake_install_dir, extra_cmake_args=())
         "-DIREE_BUILD_TESTS=OFF",
         "-DPython3_EXECUTABLE={}".format(sys.executable),
         "-DCMAKE_BUILD_TYPE={}".format(cfg),
-        get_env_cmake_option(
-            "IREE_HAL_DRIVER_VULKAN",
-            "OFF" if platform.system() == "Darwin" else "ON",
-        ),
         get_env_cmake_list("IREE_EXTERNAL_HAL_DRIVERS", ""),
         get_env_cmake_option("IREE_ENABLE_CPUINFO", "ON"),
     ] + list(extra_cmake_args)