Feature Request: Update inventory before exiting, even on error, cancel, or timeout.

Updating the inventory (sending inventory events) before exiting should make the inventory more up to date when `applier.Run` is cancelled (ex: from global timeout) or errors (ex: from poller error).

If needed, this feature could be optional with an UpdateInventoryOnError option, or similar.

/cc @haiyanmeng @Liujingfang1 @janetkuo (Config Sync stakeholders)

Start by tracing applier.Run and the inventory-event update path mentioned in the issue. Determine how cancellation, poller errors, and timeouts currently exit, and whether an UpdateInventoryOnError option is needed. Done means inventory is updated before each requested error, cancellation, or timeout exit, with behavior covered by relevant tests.

Written by the indexing model from the issue text.