Migrate Linux Arm Host Engine to engine v2. (#41555)

The artifacts from legacy and engine v2 builders are identical. This PR is moving the legacy builder to staging and updates engine v2 build to upload the artifacts to production.

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

.ci.yaml

@@ -243,6 +243,7 @@ targets:
       - "**.py" # Run pylint on the fastest clang-tidy builder.
 
   - name: Linux Arm Host Engine
+    bringup: true
     recipe: engine/engine_arm
     properties:
       add_recipes_cq: "true"

ci/builders/linux_arm_host_engine.json

@@ -8,7 +8,8 @@
                     "base_path": "out/linux_profile_arm64/zip_archives/",
                     "include_paths": [
                         "out/linux_profile_arm64/zip_archives/linux-arm64-profile/linux-arm64-flutter-gtk.zip"
-                    ]
+                    ],
+                    "realm": "production"
                 }
             ],
             "drone_dimensions": [
@@ -45,7 +46,8 @@
                         "out/linux_debug_arm64/zip_archives/linux-arm64/font-subset.zip",
                         "out/linux_debug_arm64/zip_archives/linux-arm64-debug/linux-arm64-flutter-gtk.zip",
                         "out/linux_debug_arm64/zip_archives/dart-sdk-linux-arm64.zip"
-                    ]
+                    ],
+                    "realm": "production"
                 }
             ],
             "drone_dimensions": [
@@ -81,7 +83,8 @@
                     "base_path": "out/linux_release_arm64/zip_archives/",
                     "include_paths": [
                         "out/linux_release_arm64/zip_archives/linux-arm64-release/linux-arm64-flutter-gtk.zip"
-                    ]
+                    ],
+                    "realm": "production"
                 }
             ],
             "drone_dimensions": [