Make network services settle and finish deleting #854

Summary

Some network services controllers write objects again and again when nothing about them changed, and some deletions wait forever. A write that changes nothing still loads Milo, Karmada and the cells. A deletion that never finishes holds a user's network and its addresses.

Goal

A controller stops writing once an object matches what it wants, and every deletion a user starts either finishes or raises a warning.

Scope

Covers networks, network contexts and interfaces, gateways and their routes, internal DNS contexts, and the anchors on the Karmada hub. Save conflicts between controllers that share an object stay out.

Acceptance criteria

• A user who deletes a Network or a Gateway sees it finish deleting, and an object that a finalizer holds for more than an hour raises a warning.
• Releasing a kept interface returns its addresses to the pool, and its network can then be deleted.
• A reconcile that finds nothing changed sends no write, for gateways' downstream routes and for internal DNS contexts and their status.
• An anchor whose upstream object is gone is collected.