Fix order refreshing after search

[atorresveiga]

Closes: #12941

Description

This pull request addresses the issue of the PTR (Pull-to-Refresh) getting stuck in the user interface after exiting the search view while the search is still in progress.

When we subscribe to the new pagedListWrapper in the activatePagedListWrapper function, the new LiveData starts off as null and does not emit any value until the list changes. We also remove the previous source by calling clearLiveDataSources. However, because _isFetchingFirstPage is a MediatorLiveData, it retains the last cached value. This leads to a problem: when we exit the search view and switch to the new activatePagedListWrapper, the screen state remains stuck in a refreshing state. This occurs because _isFetchingFirstPage does not reflect the state of the current activatePagedListWrapper (which is null), but rather the last cached value.

To resolve this issue, I have chosen to reset the LiveData to its default values within the clearLiveDataSources function.

I considered an alternative solution that involved adding an initial value to the PagedListWrapper LiveData. However, since this class is utilized in other projects as well, I opted for the current solution to minimize the impact on our code and prevent any regressions in those other projects.

Steps to reproduce

1. Go to Orders
2. Tap on Search
3. Search anything
4. Get back to order while PTR is still displayed
5. Notice that PTR is there forever now, and PTR is not possible for the orders at all

Testing information

• Follow the steps to reproduce and check that the issue is not present in this PR-

The tests that have been performed

• Checked that the issue is not present after following the Steps to reproduce
• Test that PTR keeps working as expected
• Test that filters keep working as expected

Images/gif

https://github.com/user-attachments/assets/8e3ef9b5-2e6c-4419-b441-648fa1b749d6

• [x] I have considered if this change warrants release notes and have added them to RELEASE-NOTES.txt if necessary. Use the "[Internal]" label for non-user-facing changes.

Reviewer (or Author, in the case of optional code reviews):

Please make sure these conditions are met before approving the PR, or request changes if the PR needs improvement:

• [x] The PR is small and has a clear, single focus, or a valid explanation is provided in the description. If needed, please request to split it into smaller PRs.
• [x] Ensure Adequate Unit Test Coverage: The changes are reasonably covered by unit tests or an explanation is provided in the PR description.
• [x] Manual Testing: The author listed all the tests they ran, including smoke tests when needed (e.g., for refactorings). The reviewer confirmed that the PR works as expected on big (tablet) and small (phone) in case of UI changes, and no regressions are added.

[wpmobilebot]

📲 You can test the changes from this Pull Request in WooCommerce-Wear Android by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce-Wear Android
	Platform	⌚️ Wear OS
	Flavor	Jalapeno
	Build Type	Debug
	Commit	6fe67594b9553f7de02f4c3e2ee0801b8d4020b9
	Direct Download	woocommerce-wear-prototype-build-pr12948-6fe6759.apk

[wpmobilebot]

📲 You can test the changes from this Pull Request in WooCommerce Android by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce Android
	Platform	📱 Mobile
	Flavor	Jalapeno
	Build Type	Debug
	Commit	6fe67594b9553f7de02f4c3e2ee0801b8d4020b9
	Direct Download	woocommerce-prototype-build-pr12948-6fe6759.apk

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 39.66%. Comparing base (9a83bcc) to head (6fe6759). Report is 5 commits behind head on trunk.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## trunk #12948 +/- ## ========================================= Coverage 39.65% 39.66% - Complexity 5949 5952 +3 ========================================= Files 1261 1261 Lines 72890 72893 +3 Branches 9973 9973 ========================================= + Hits 28904 28910 +6 + Misses 41413 41411 -2 + Partials 2573 2572 -1 ```

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