fixup! Bug 27476: Implement about:torconnect captive portal within Tor Browser

Fixes #40507 (closed)

When applying an incremental update fails, the updater will automatically attempt to download and apply a full update. The problem is that this all happens before bootstrap; the normal flow is bootstrap -> check for update -> download incremental update -> reboot browser -> apply incremental update and download/apply full update on failure -> bootstrap

Without this patch, the full download fails, and the whole process starts over so you get stuck in an infinite partial update -> failure loop.

Users who currently have a corrupted Tor Browser install will need use the legacy tor-launcher to get out of the update loop.

This patch adds a similar check for the pre-bootstrap failure case in UpdateService.onStopRequest() to mirror the existing check for offline.