Wait 30 more seconds after Tor has bootstrapped, before checking for upgrades (Closes: #6728).

We run many things in parallel at session startup, and in some cases we are not
able to check for upgrades due to memory exhaustion. Waiting a bit might help.

config/chroot_local-includes/usr/local/bin/tails-upgrade-frontend-wrapper

@@ -64,6 +64,7 @@ while ! sudo -n -u debian-tor /usr/local/sbin/tor-has-bootstrapped ; do
    sleep 10
 done
 
+sleep 30
 
 check_free_memory "$MIN_MEMFREE" "$MIN_TOTAL_MEMFREE"