Core Data: Update storage usage for BlazeStore

[itsmeichigo]

Part of #14122

Description

This PR migrates the storage usage for BlazeStore:

• Replaced the deprecated usage of writerDerivedStorage with performAndSave method to ensure write operations are put in the same writer queue.
• Optimize fetch requests when upserting campaign list items by using a single fetch for all campaigns instead of separate requests for each.

Steps to reproduce

• Log in to a store eligible for Blaze.
• Navigate to Menu tab > Blaze.
• If the store has existing campaigns, confirm that loading campaigns work with pagination.
• Create a new campaign. Confirm that campaign objectives, targeted devices, languages, topics can be loaded successfully. Reopening these sections should show data immediately as they are cached in the storage.
• Ensure that campaign creation succeeds.

Testing information

Tested on simulator iPhone 16 Pro iOS 18.1 and confirmed that:

• Loading Blaze campaigns work correctly with pagination.
• Loading campaign objectives, targeted devices, languages and topics works correctly.
• Campaign creation succeeds as expected.

All existing unit tests in BlazeStoreTests should still pass.

Screenshots

N/A

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• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

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:

• 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.
• Ensure Adequate Unit Test Coverage: The changes are reasonably covered by unit tests or an explanation is provided in the PR description.
• 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 all devices (phone/tablet) and no regressions are added.

[wpmobilebot]

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

	App Name	WooCommerce iOS
	Build Number	pr14532-bc1f44f
	Version	21.2
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	bc1f44f
	App Center Build	WooCommerce - Prototype Builds #11887

Automatticians: You can use our internal self-serve MC tool to give yourself access to App Center if needed.

[selanthiraiyan]

Nice work, Huong!

The code LGTM and tests as expected. 🚀