Flaky messaging-integration-test

### Description

The messaging-integration-test has been failing about half the time lately.

I'm going to disable the test until the issue is resolved.

Revert #12206 when this is fixed

For example, see https://github.com/firebase/firebase-ios-sdk/actions/runs/7226772854/job/19693060191?pr=12204#step:9:1133:

```
Failing tests:
FIRMessagingPubSubTest.testSubscribeTopic()
FIRMessagingPubSubTest.testUnsubscribeTopic()
FIRMessagingTokenRefreshTests.testDeleteDefaultTokenWithTokenRefreshDelegatesAndNotifications()
```

### Reproducing the issue

See https://github.com/firebase/firebase-ios-sdk/blob/main/.github/workflows/messaging.yml#L26

### Firebase SDK Version

10.19.0

### Xcode Version

14.2

### Installation Method

CocoaPods

### Firebase Product(s)

Messaging

### Targeted Platforms

iOS

### Relevant Log Output

_No response_

### If using Swift Package Manager, the project's Package.resolved

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```json

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### If using CocoaPods, the project's Podfile.lock

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