[Tooling] Don't cancel in-progress Issue Validation GitHub Action jobs

[iangmaia]

This PR depends on https://github.com/Automattic/dangermattic/pull/82

This PR is an update to the validate-issues.yml workflow, using the new parameter cancel-running-jobs to prevent GitHub Actions to cancel currently running jobs in the same concurrency group.

[dangermattic]

	1 Warning
:warning:	This PR is assigned to the milestone 25.4. 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.

Generated by :no_entry_sign: Danger

[wpmobilebot]

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

	App Name	Jetpack Alpha
	Configuration	Release-Alpha
	Build Number	pr23607-bfb4566
	Version	25.3
	Bundle ID	com.jetpack.alpha
	Commit	bfb4566e8d552ee0b385146399c436fd5594619e
	App Center Build	jetpack-installable-builds #9750

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[wpmobilebot]

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

	App Name	WordPress Alpha
	Configuration	Release-Alpha
	Build Number	pr23607-bfb4566
	Version	25.3
	Bundle ID	org.wordpress.alpha
	Commit	bfb4566e8d552ee0b385146399c436fd5594619e
	App Center Build	WPiOS - One-Offs #10706

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