Do not update image on UI if the downloading task is cancelled

[crazytonyli]

Description

The first commit contains the core change, which skips updating the UI if the fetching image task was canceled.

[dangermattic]

	1 Warning
⚠️	This PR is assigned to the milestone 26.9. This milestone is due in less than 4 days. Please make sure to get it merged by then or assign it to a milestone with a later deadline.

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

	App Name	WordPress
	Configuration	Release-Alpha
	Build Number	32033
	Version	PR #25501
	Bundle ID	org.wordpress.alpha
	Commit	2341d08
	Installation URL	16jn6hm4p8cm8

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[wpmobilebot]

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

	App Name	Jetpack
	Configuration	Release-Alpha
	Build Number	32033
	Version	PR #25501
	Bundle ID	com.jetpack.alpha
	Commit	2341d08
	Installation URL	2nibjsrcidnm8

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[jkmassel]

Seems worth a try