revert(search): drop unnecessary reindex_for_search guard; trim automation_rule comments

The guard was dead code: should_index? is only true when searchkick is loaded
(both gated on advanced_search_allowed?), so #reindex is always defined when the
callback fires. It only masked a flaky develop-owned message_spec and contradicts
the fail-loudly-on-impossible-state guideline. Also trim verbose comments in
automation_rule.rb.

app/models/automation_rule.rb

@@ -38,9 +38,7 @@ class AutomationRule < ApplicationRecord
   validate :execution_delay_supported_event
 
   after_update_commit :reauthorized!, if: -> { saved_change_to_conditions? }
-  # Rows already armed under the old definition must not fire on a config the rule no longer
-  # has (different delay, trigger, conditions, or actions). Delete rather than skip so the
-  # freed episode slot lets the new definition re-arm on the next matching event.
+  # Discard rows armed under the old definition; they re-arm on the next matching event.
   after_update :discard_stale_pending_executions, if: :execution_config_changed?
 
   scope :active, -> { where(active: true) }
@@ -115,11 +113,8 @@ class AutomationRule < ApplicationRecord
     errors.add(:execution_delay, 'cannot be used with attribute_changed conditions.')
   end
 
-  # Conversation-level events (anything but message_created) key their episode on
-  # status_changed_at alone. A delayed condition on any other attribute (assignee, team,
-  # priority, ...) would collapse distinct qualifying periods into one episode and could
-  # fire on a stale window, so only status conditions are supported until episodes track
-  # per-attribute change times.
+  # Conversation-level episodes key on status_changed_at alone, so only status conditions
+  # can be delayed; other attributes would collapse distinct periods into one episode.
   def execution_delay_supported_event
     return if execution_delay.blank? || conditions.blank? || event_name == 'message_created'
     return if conditions.all? { |obj| obj['attribute_key'] == 'status' }
@@ -133,7 +128,7 @@ class AutomationRule < ApplicationRecord
   end
 
   def discard_stale_pending_executions
-    # Includes stale processing rows: the sweep would otherwise reclaim and fire them.
+    # armed = pending + stale processing, which the sweep would otherwise reclaim.
     pending_executions.armed.delete_all
   end
 

app/models/message.rb

@@ -452,10 +452,6 @@ class Message < ApplicationRecord
   end
 
   def reindex_for_search
-    # searchkick (which defines #reindex) is only mixed in when advanced_search_allowed? is true
-    # at boot; guard so a should_index? true without a loaded index can't raise NoMethodError.
-    return unless respond_to?(:reindex)
-
     reindex(mode: :async)
   end
 end