feat(migration): Migrate Activity records to use the SET_ESCALATING type (#49846)

## Objective:
We want to use the the new ActivityType.SET_ESCALATING and convert
relevant existing rows that use ActivityType.SET_UNRESOLVED. The
affected rows will have a key of `forecast` in the data column.

Total number of rows in the query: 510685
https://redash.getsentry.net/queries/4193/source

---------

Co-authored-by: Mark Story <mark@mark-story.com>
Co-authored-by: Snigdha Sharma <snigdha.sharma@sentry.io>

migrations_lockfile.txt

@@ -6,5 +6,5 @@ To resolve this, rebase against latest master and regenerate your migration. Thi
 will then be regenerated, and you should be able to merge without conflicts.
 
 nodestore: 0002_nodestore_no_dictfield
-sentry: 0475_backfill_groupedmessage_unresolved_none_status
+sentry: 0476_convert_unresolved_to_set_escalating_activitytype
 social_auth: 0001_initial

src/sentry/migrations/0476_convert_unresolved_to_set_escalating_activitytype.py

@@ -0,0 +1,47 @@
+# Generated by Django 2.2.28 on 2023-05-26 07:32
+
+from django.db import migrations
+
+from sentry.new_migrations.migrations import CheckedMigration
+from sentry.types.activity import ActivityType
+from sentry.utils.query import RangeQuerySetWrapperWithProgressBar
+
+
+def convert_to_set_escalating(apps, schema_editor):
+    Activity = apps.get_model("sentry", "Activity")
+
+    for activity in RangeQuerySetWrapperWithProgressBar(
+        Activity.objects.filter(type=ActivityType.SET_UNRESOLVED.value)
+    ):
+
+        if not activity.data.get("forecast"):
+            continue
+
+        activity.type = ActivityType.SET_ESCALATING
+        activity.save(update_fields=["type"])
+
+
+class Migration(CheckedMigration):
+    # This flag is used to mark that a migration shouldn't be automatically run in production. For
+    # the most part, this should only be used for operations where it's safe to run the migration
+    # after your code has deployed. So this should not be used for most operations that alter the
+    # schema of a table.
+    # Here are some things that make sense to mark as dangerous:
+    # - Large data migrations. Typically we want these to be run manually by ops so that they can
+    #   be monitored and not block the deploy for a long period of time while they run.
+    # - Adding indexes to large tables. Since this can take a long time, we'd generally prefer to
+    #   have ops run this and not block the deploy. Note that while adding an index is a schema
+    #   change, it's completely safe to run the operation after the code has deployed.
+    is_dangerous = True
+
+    dependencies = [
+        ("sentry", "0475_backfill_groupedmessage_unresolved_none_status"),
+    ]
+
+    operations = [
+        migrations.RunPython(
+            convert_to_set_escalating,
+            reverse_code=migrations.RunPython.noop,
+            hints={"tables": ["sentry_activity"]},
+        )
+    ]