Add grace period to project stuck creating alert

[scotwells]

Summary

Adds a 2-minute grace period to the ProjectStuckCreatingSLOViolation alert rule. Previously, the alert fired immediately (for: 0s), which meant any brief gap in monitoring data would trigger a false page.

Context

On March 28, a short monitoring database disruption caused this alert to fire incorrectly. The 2-minute grace period gives the system time to recover from brief outages before paging on-call.

Tracking issue: https://github.com/datum-cloud/infra/issues/2059

[github-actions]

🤖 I automatically added missing newlines at the end of 1 file(s) in this PR.

All files should now end with a newline character as per coding standards.

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✅ scotwells
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[cla-assistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you all sign our Contributor License Agreement before we can accept your contribution.
1 out of 2 committers have signed the CLA.

✅ scotwells
❌ github-actions[bot]
_{You have signed the CLA already but the status is still pending? Let us recheck it.}