Various improvements for the notification of scheduled model regression tests

[HotThoughts]

Proposed changes:

• Resolve Improve slack notification for the scheduled model regression test workflow #8268 and Add tolerance to automatic alerts on scheduled nlu regression tests #8482
• Do not alert slack and create an issue if there is already an issue for it. We check issue title and body for duplicates.
• Allow tolerance to performance drops. Don't alert slack and don't create an issue if the performance drops within the tolerance.
• Rewrite GitHub issue steps using action/github-scripts

Definition of Done:

• the workflow can analyze performance correctly
• the workflow will prepare issues if performance drops
• the workflow will skip the creation of issue steps if found existing one or performance is good
• Notify slack properly with the right links

The cases that tested:

• test run failed, but related issue found or test run successed -> don't notify slack nor create issue
• test run failed, not related issue found -> notify slack + create issue
• performance drops, no related issue found -> notify slack+ create issue
• performance is good -> don't notify slack nor create issue

TODOs before merge

• remove fake data
• uncomment config
• update slack webhook

[HotThoughts]

@tczekajlo this one is almost done. The performance analyses and issue creation steps are tested and ready to review. 🤘🏻

One last step is to test the slack notification. We were using the webhook SLACK_TEST_WEBHOOK. Do we still have it in our secret?

[tczekajlo]

@tczekajlo this one is almost done. The performance analyses and issue creation steps are tested and ready to review. 🤘🏻

One last step is to test the slack notification. We were using the webhook SLACK_TEST_WEBHOOK. Do we still have it in our secret?

Coool, yes, you can use the secret.

[tczekajlo]

I've left small suggestions 😄

[tczekajlo]

LGTM 🎖️