chore(severity): Register option for high priority alerts (#61367)

Setting option values in
https://github.com/getsentry/sentry-options-automator/pull/498

src/sentry/options/defaults.py

@@ -743,6 +743,13 @@ register(
     flags=FLAG_AUTOMATOR_MODIFIABLE,
 )
 
+register(
+    "issues.severity.high-priority-alerts-projects-allowlist",
+    type=Sequence,
+    default=[],
+    flags=FLAG_ALLOW_EMPTY | FLAG_AUTOMATOR_MODIFIABLE,
+)
+
 
 # ## sentry.killswitches
 #