Remove unused python_binary build artifacts (#28111)

Author: richkadel

tools/fuchsia/dart/BUILD.gn

@@ -3,14 +3,9 @@
 # found in the LICENSE file.
 
 import("//flutter/tools/fuchsia/dart/toolchain.gni")
-import("//flutter/tools/fuchsia/python/python_binary.gni")
 import("//flutter/tools/fuchsia/sdk/sdk_targets.gni")
 import("//flutter/tools/fuchsia/toolchain/basic_toolchain.gni")
 
-python_binary("gen_dart_package_config") {
-  main_source = "gen_dart_package_config.py"
-}
-
 if (current_toolchain == default_toolchain) {
   # A toolchain dedicated to processing and analyzing Dart packages.
   # The only targets in this toolchain are action() targets, so it

tools/fuchsia/dart/dart_package_config.gni

@@ -97,10 +97,7 @@ template("dart_package_config") {
     if (!defined(deps)) {
       deps = []
     }
-    deps += [
-      ":$generate_target",
-      "//flutter/tools/fuchsia/dart:gen_dart_package_config",
-    ]
+    deps += [ ":$generate_target" ]
 
     metadata = {
       # Add a barrier here to avoid double of inclusion of elements listed in