fix invalid domain block severities

This commit fixes any invalid domain block severities by setting them to
2 if they are bigger than 2 or 0 if they are smaller than 0.
This ensures that the domain block severities are always within the valid
range of 0 to 2.

db/migrate/20240220082519_fix_invalid_domain_block_severities.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+class FixInvalidDomainBlockSeverities < ActiveRecord::Migration[7.1]
+  disable_ddl_transaction!
+
+  def up
+    safety_assured do
+      execute <<~SQL.squish
+        UPDATE domain_blocks
+        SET severity = CASE WHEN severity > 2 THEN 2 WHEN severity < 0 THEN 0 END
+        WHERE severity > 2 OR severity < 0 RETURNING id;
+      SQL
+    end
+  end
+
+  def down; end
+end