vinyl: ignore quota timeout during bootstrap from master

During initial join, a replica receives all data accumulated on the
master for its whole lifetime, which may be quota a lot. If the network
connection is fast enough, the replica might fail to keep up with dumps,
in which case replication fails with ER_VY_QUOTA_TIMEOUT. To avoid that,
let's ignore quota timeout until bootstrap is complete.

Note, replication may still fail during the 'subscribe' stage for the
same reason, but it's unlikely, because the rate at which the master
sends data is limited by the number of requests served by the master per
a unit of time, and it should become nearly impossible once throttling
is introduced (See #1862).

Closes #2873