Remove usage of deprecated Fuchsia event source (#37641)

This capability is being removed by the Fuchsia platform (https://fuchsia-review.git.corp.google.com/c/fuchsia/+/758606), but is currently blocked on this usage.

This change simply removes the capability from this tests, where it doesn't seem to be used at all.

Author: crjohns

shell/platform/fuchsia/flutter/tests/integration/text-input/meta/text-input-test.cml

@@ -17,13 +17,6 @@
     program: {
         binary: "bin/app",
     },
-    use: [
-        { protocol: "fuchsia.sys2.EventSource" },
-        {
-            event: "stopped",
-            from: "framework",
-        },
-    ],
     offer: [
         {
             protocol: [