Gate DevTools test to fix CI

This test started failing recently in older versions of React because
the Scheduler priority inside a microtask is Normal instead of
Immediate. This is expected because microtasks are not Scheduler tasks;
it's an implementation detail. I gated the test to only run in the older
versions of React, because it's a regression test for the legacy
Suspense renderer. So it doesn't really need to run for new versions,
because the legacy renderer is deprecated and will soon be removed.

Test plan:

```
yarn test --build --project devtools --release-channel=experimental --reactVersion 18.0 --watch
```

Author: acdlite

packages/react-devtools-shared/src/__tests__/profilingCache-test.js

@@ -938,7 +938,7 @@ describe('ProfilingCache', () => {
     }
   });
 
-  // @reactVersion >= 18.0
+  // @reactVersion < 18.2
   it('should handle unexpectedly shallow suspense trees', () => {
     const container = document.createElement('div');
 
@@ -963,7 +963,7 @@ describe('ProfilingCache', () => {
             2 => 0,
           },
           "passiveEffectDuration": null,
-          "priorityLevel": "Normal",
+          "priorityLevel": "Immediate",
           "timestamp": 0,
           "updaters": [
             {