Revert "Reland "Add support for GCS deps""

This reverts commit d94a03f21e.

Reason for revert: PLATFORM_MAPPING import issue

Original change's description:
> Reland "Add support for GCS deps"
>
> This is a reland of commit 3eedee7b55
>
> Original change's description:
> > Add support for GCS deps
> >
> > Also take out GCS calling logic from download_google_storage and
> > into call_google_storage.
> >
> > GCS deps look like:
> >    'src/third_party/node/linux': {
> >        'dep_type': 'gcs',
> >        'condition': 'checkout_linux',
> >        'bucket': 'chromium-nodejs/20.11.0',
> >        'object_name': '46795170ff5df9831955f163f6966abde581c8af',
> >        'sha256sum': '887504c37404898ca41b896f448ee6d7fc24179d8fb6a4b79d028ab7e1b7153d',
> >    },
> >
> >    'src/third_party/llvm-build/Release+Asserts': {
> >        'dep_type': 'gcs',
> >        'condition': 'checkout_linux',
> >        'bucket': 'chromium-browser-clang',
> >        'object_name': 'Linux_x64/clang-llvmorg-18-init-17730-gf670112a-2.tar.xz',
> >        'sha256sum': '1e46df9b4e63c074064d75646310cb76be2f19815997a8486987189d80f991e8',
> >    },
> >
> > Example directory for src/third_party/node/linux after gclient sync:
> > - tar_file.gz is the downloaded file from GCS.
> > - node_linux_x64/ is extracted in its path.
> > - `hash` contains the sha of GCS filename.
> > ```
> > chromium/src/ ->
> >    third_party/node/linux/ ->
> >        hash, tar_file.gz, node_linux_x64/
> > ```
> >
> > Bug: b/324418194
> > Change-Id: Ibcbbff27e211f194ddb8a08494af56570a84a12b
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5299722
> > Commit-Queue: Stephanie Kim <kimstephanie@google.com>
> > Reviewed-by: Joanna Wang <jojwang@chromium.org>
>
> Bug: b/324418194
> Change-Id: I8b960f6dd3534658a9ee0b7688e68eaa15df1444
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5334791
> Commit-Queue: Stephanie Kim <kimstephanie@google.com>
> Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>
> Reviewed-by: Joanna Wang <jojwang@chromium.org>

Bug: b/324418194
Change-Id: I28bc0ba838a1135ff882cd88b77dbb2cb4b85b82
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5345022
Reviewed-by: Joanna Wang <jojwang@chromium.org>
Commit-Queue: Stephanie Kim <kimstephanie@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>

gclient_eval.py

@@ -131,14 +131,6 @@ _GCLIENT_DEPS_SCHEMA = _NodeDictSchema({
             schema.Optional('dep_type', default='cipd'):
             str,
         }),
-        # GCS content.
-        _NodeDictSchema({
-            'bucket': str,
-            'object_name': str,
-            'sha256sum': str,
-            schema.Optional('condition'): str,
-            schema.Optional('dep_type', default='gcs'): str,
-        }),
     ),
 })