🔧 chore(pagerduty): Support "default" for custom severity config

[iamrajjoshi]

As part of ACI Notification Action, we need to consolidate the configuration of Actions between the metric and issue alert registries into a "superset". This PR will get us there for Pagerduty.

Currently we store configuration for Pagerduty AlertRuleTriggerActions in sentry_app_config as follows: {"priority":"critical"}. We have something similar for Issue Alerts, so we are good there.

However, these is 1 thing that isn't aligned:
Issue Alerts have the following option for severity/priority: "default", "critical", "warning", "error", "info"
Metric Alerts have: "critical", "warning", "error", "info"

Notice that "default" is missing. You can also confirm this by trying to configure a pager duty on both Issue/Metric UI - Metric Alert action doesn't have a default option.

Issue

Metric

---

In the future when Actions can be attached to Workflows that will invoke either Issue/Metric registries, we need the configuration to be the same for the API for Actions to be the same for all automations.

What this PR does is allows us to pass "default" as a severity to Metric Alert action handler and it will use the default severity behavior that is determined here:

sentry/src/sentry/integrations/pagerduty/utils.py

Lines 100 to 107 in 9ffcb55

	severity = "info"
	if new_status == IncidentStatus.CRITICAL:
	severity = "critical"
	elif new_status == IncidentStatus.WARNING:
	severity = "warning"
	elif new_status == IncidentStatus.CLOSED:
	severity = "info"

---

I tried explaining the reasoning here, but you need more clarifications, lmk!

references:

sentry/src/sentry/integrations/pagerduty/client.py

Line 20 in 9ffcb55

PagerdutySeverity = Literal["default", "critical", "warning", "error", "info"]

https://www.notion.so/sentry/ACI-Notification-Type-Problem-16f8b10e4b5d80f5a41af031daf3459b#1708b10e4b5d800d8789e988e1c6c25e

closes https://getsentry.atlassian.net/browse/ACI-108

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

✅ All tests successful. No failed tests found.

Additional details and impacted files

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  Branches    21179    21179              
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+ Hits       470916   472098    +1182     
+ Misses      66602    66480     -122     
  Partials      348      348              

[cathteng]

PAGERDUTY_DEFAULT_SEVERITY is a string?

Suggested change

	if severity is not None and severity in PAGERDUTY_DEFAULT_SEVERITY:
	if severity is not None and severity in PagerdutySeverity:

[iamrajjoshi]

whoops it needs to be severity == PAGERDUTY_DEFAULT_SEVERITY

[cathteng]

does this test assert that we used the default severity mapping for metric alerts?

[iamrajjoshi]

yeah it makes sure if the priority is default, (meaning we have added a config) it will still use the default priority.