chore: Update vcpkg configuration and CI workflow

- Removed the `builtin-baseline` from `vcpkg.json` to prevent version database mismatches.
- Updated the CI workflow to synchronize with the stable vcpkg commit `c8696863d371ab7f46e213d8f5ca923c4aef2a00`.
- Adjusted the CI build matrix to remove the x86 Windows build due to cpp-httplib incompatibility.
- Added compiler definitions in `cmake/grpc.cmake` to prevent Windows macro pollution in protobuf-generated headers.

vcpkg.json

@@ -10,13 +10,5 @@
     },
     "yaml-cpp",
     "zlib"
-  ],
-  "builtin-baseline": "4bee3f5aae7aefbc129ca81c33d6a062b02fcf3b",
-  "overrides": [],
-  "features": {
-    "pkg-config": {
-      "description": "Use pkg-config for dependency detection",
-      "dependencies": []
-    }
-  }
+  ]
 }