[CQ] remove removed InspectorGroupManagerService (#8125)

The `InspectorGroupManagerService` was removed a bit ago and this
straggling `projectService` registration is dead.

---

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portions to this PR.

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Author: pq

resources/META-INF/plugin.xml

@@ -444,9 +444,6 @@
     <projectService serviceInterface="io.flutter.editor.ActiveEditorsOutlineService"
                     serviceImplementation="io.flutter.editor.ActiveEditorsOutlineService"
                     overrides="false"/>
-    <projectService serviceInterface="io.flutter.inspector.InspectorGroupManagerService"
-                    serviceImplementation="io.flutter.inspector.InspectorGroupManagerService"
-                    overrides="false"/>
 
     <iconProvider implementation="io.flutter.project.FlutterIconProvider" order="first"/>
 

resources/META-INF/plugin_template.xml

@@ -352,9 +352,6 @@
     <projectService serviceInterface="io.flutter.editor.ActiveEditorsOutlineService"
                     serviceImplementation="io.flutter.editor.ActiveEditorsOutlineService"
                     overrides="false"/>
-    <projectService serviceInterface="io.flutter.inspector.InspectorGroupManagerService"
-                    serviceImplementation="io.flutter.inspector.InspectorGroupManagerService"
-                    overrides="false"/>
 
     <iconProvider implementation="io.flutter.project.FlutterIconProvider" order="first"/>