Fix flaky verifyOnAppComesFromBackgroundCalled test

[irfano]

This increases sleep time in verifyOnAppComesFromBackgroundCalled test case.

verifyOnAppComesFromBackgroundCalled fails rarely on Firebase Test Lab environment.
I ran the application multiple times on emulator and debugged the order of related functions. It's like this:

1. App is launched,
2. Application's onCreate runs,
3. AppInitializer's onAppComesFromBackground runs,
4. WordPress.appIsInTheBackground is set to false.
5. If we run verifyOnAppComesFromBackgroundCalled test case, the test runs in this step.

But in FTL environment, step 4 works before 2 sometimes. That causes the test to fail. We don't use WordPress.appIsInTheBackground for instant checks after app launch, so it's totally safe to increase sleep time for verifyOnAppComesFromBackgroundCalled. The time was set to 200, but it can be increased if it still fails.

To test:
Run verifyOnAppComesFromBackgroundCalled test case on FTL a couple times.

Regression Notes

1. Potential unintended areas of impact
   None

2. What I did to test those areas of impact (or what existing automated tests I relied on)
   N/A

3. What automated tests I added (or what prevented me from doing so)
   Updated current test.

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[wpmobilebot]

📲 You can test these changes on Jetpack by downloading jetpack-installable-build-pr17370-81120a0.apk

	💡 Scan this QR code with your Android phone to download and install the APK directly on it.
	App	Jetpack
	Build Flavor	Jalapeno
	Build Type	Debug
	Commit	81120a0

Note: This installable build uses the JalapenoDebug build flavor, and does not support Google Login.

[wpmobilebot]

📲 You can test these changes on WordPress by downloading wordpress-installable-build-pr17370-81120a0.apk

	💡 Scan this QR code with your Android phone to download and install the APK directly on it.
	App	WordPress
	Build Flavor	Jalapeno
	Build Type	Debug
	Commit	81120a0

Note: This installable build uses the JalapenoDebug build flavor, and does not support Google Login.

[pachlava]

Thanks a lot for working on this @irfano 👋

I can see that Instrumented Tests are green on FTL, and I think it's enough to have the change merged. Because the test rarely fails, the best way is to let the change into the wild and see how it behaves in the long run 👍 🚀