db: Retry failed rollbacks if they are due to transient errors
db: Retry failed rollbacks if they are due to transient errors

This avoids leaving the connection in a bad state, where a transaction is
already in progress and another one can't be started.

Signed-off-by: Free Ekanayaka <04111f73b2d444cf053b50d877d79556bf34f55a@canonical.com>

stgraber/lxd,stgraber/lxd,atxwebs/lxd,hallyn/lxd,stgraber/lxd,lxc/lxd,lxc/lxd,lxc/lxd,atxwebs/lxd,hallyn/lxd,lxc/lxd,stgraber/lxd,hallyn/lxd,lxc/lxd,hallyn/lxd,lxc/lxd,hallyn/lxd,atxwebs/lxd,stgraber/lxd,hallyn/lxd,stgraber/lxd,stgraber/lxd,atxwebs/lxd,lxc/lxd