[luci] Reference the right fuchsia CIPD and upload only once (flutter/engine#9998)

* [luci] Reference the right fuchsia CIPD and upload only once

Also only upload is os is linux

* copy cipd

engine/src/flutter/tools/fuchsia/build_fuchsia_artifacts.py

@@ -10,6 +10,7 @@
 import argparse
 import errno
 import os
+import platform
 import shutil
 import subprocess
 import sys
@@ -19,6 +20,9 @@ _src_root_dir = os.path.join(_script_dir, '..', '..', '..')
 _out_dir = os.path.join(_src_root_dir, 'out')
 _bucket_directory = os.path.join(_out_dir, 'fuchsia_bucket')
 
+def IsLinux():
+  return platform.system() == 'Linux'
+
 def RunExecutable(command):
   subprocess.check_call(command, cwd=_src_root_dir)
 
@@ -80,7 +84,6 @@ def BuildBucket():
   CopyToBucket('fuchsia_profile/dart_runner', 'flutter/profile/dart_runner')
   CopyToBucket('fuchsia_release/dart_runner', 'flutter/release/dart_runner')
 
-
   CopyToBucket('fuchsia_debug/icudtl.dat', 'flutter/debug/icudtl.dat')
   CopyToBucket('fuchsia_profile/icudtl.dat', 'flutter/profile/icudtl.dat')
   CopyToBucket('fuchsia_release/icudtl.dat', 'flutter/release/icudtl.dat')
@@ -91,7 +94,7 @@ def ProcessCIPDPakcage(upload, engine_version):
   cipd_yaml = os.path.join(_script_dir, 'fuchsia.cipd.yaml')
   CopyFiles(cipd_yaml, os.path.join(_bucket_directory, 'fuchsia.cipd.yaml'))
 
-  if upload:
+  if upload and IsLinux():
     command = [
       'cipd',
       'create',

engine/src/flutter/tools/fuchsia/fuchsia.cipd.yaml

@@ -0,0 +1,6 @@
+package: flutter/fuchsia
+description: Flutter Fuchsia Artifacts
+install_mode: copy
+data:
+  # Don't modify this! This is where the build script put all bucket artifacts.
+  - dir: flutter/