Remove 'Linux mac_clangd' in favor of 'Mac clangd' (#56082)

Follow up to #56014

`Mac clangd` is [passing as a standalone build](https://ci.chromium.org/ui/p/flutter/builders/staging/Mac%20clangd/60/overview) (<10 minutes).  Move it out of bringup and remove `Linux mac_clangd`.

flutter/flutter#157275

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

Author: jmagman

.ci.yaml

@@ -503,20 +503,8 @@ targets:
     drone_dimensions:
       - os=Mac-13|Mac-14
 
-  # TODO(jmagman) Replace with "Mac clangd" when bringup is removed.
-  - name: Linux mac_clangd
-    recipe: engine_v2/engine_v2
-    timeout: 90
-    # Do not remove(https://github.com/flutter/flutter/issues/144644)
-    # Scheduler will fail to get the platform
-    drone_dimensions:
-      - os=Linux
-    properties:
-      config_name: mac_unopt_debug_no_rbe
-
   - name: Mac clangd
     recipe: engine_v2/builder
-    bringup: true
     properties:
       config_name: mac_clangd
       cpu: x86