Action: wu_network_pre_delete
Fires before a network is deleted.
Use this hook to tear down out-of-band resources linked to the network — for example the Multi-Tenancy addon's Multi_Tenancy_Integration uses it to drop the isolated MySQL database, MySQL user, and credential for customer-owned networks. Runs BEFORE the core delete_network() call so consumers can still look up related rows by network_id before WordPress wipes the network metadata.