Avoid updating Listener status updated time on every Gateway reconcile

[rainest]

Gateway reconciles update Listener statuses with the current time. Listener Conditions (Ready, Conflicted) etc. are generated from scratch based on the current Listeners, setting the observed generation to the current generation.

We should review options to only update the Listener status time if the Listener status has actually changed, and leaving the original observed generation on Conditions if they were already present. This may require adding logic to remove outdated Conditions if we can no longer replace the entire Listener status and associated conditions with an updated version.

Stub AC:

• Remove TODO and TODO