Unblock auto roller.

Error message:
Traceback (most recent call last):
  File "/b/s/w/ir/cache/builder/src/tools_webrtc/autoroller/roll_deps.py", line 778, in <module>
    sys.exit(main())
  File "/b/s/w/ir/cache/builder/src/tools_webrtc/autoroller/roll_deps.py", line 748, in main
    raise RollError('WebRTC DEPS entries are missing from Chromium: %s.\n'
__main__.RollError: WebRTC DEPS entries are missing from Chromium: ['src/third_party/fuchsia-sdk/sdk'].
Remove them or add them to either WEBRTC_ONLY_DEPS or DONT_AUTOROLL_THESE.

src/third_party/fuchsia-sdk/sdk has been removed from
https://crrev.com/c/3914609.

Bug: None
Change-Id: Ic2b7b39ffd1a3e5fb9bb73ddb1318a5e36b0bc30
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/276720
Reviewed-by: Andrey Logvin <landrey@google.com>
Commit-Queue: Daniel.L (Byoungchan) Lee <daniel.l@hpcnt.com>
Cr-Commit-Position: refs/heads/main@{#38199}

DEPS

@@ -356,17 +356,6 @@ deps = {
       'dep_type': 'cipd',
   },
 
-  'src/third_party/fuchsia-sdk/sdk': {
-      'packages': [
-          {
-              'package': Var('fuchsia_sdk_cipd_prefix') + '${{platform}}',
-              'version': Var('fuchsia_version'),
-          },
-      ],
-      'condition': 'checkout_fuchsia',
-      'dep_type': 'cipd',
-  },
-
   'src/third_party/hamcrest': {
       'packages': [
           {
@@ -2323,6 +2312,19 @@ hooks = [
     'condition': 'checkout_mac',
     'action': ['python3', 'src/build/mac_toolchain.py'],
   },
+
+  {
+    'name': 'Download Fuchsia SDK from GCS',
+    'pattern': '.',
+    'condition': 'checkout_fuchsia',
+    'action': [
+      'python3',
+      'src/build/fuchsia/update_sdk.py',
+      '--cipd-prefix={fuchsia_sdk_cipd_prefix}',
+      '--version={fuchsia_version}',
+    ],
+  },
+
   {
     'name': 'Download Fuchsia system images',
     'pattern': '.',