BUG-8494: fix throttling during reconnect

ReconnectForwarder is called from differing code-paths: the one is
during replay when we are dealing with late requests (those which have
been waiting while we replaying), the other is subsequent user requests.

The first one should not be waiting on the queue, as the requests have
already entered it, hence have payed the cost of entry. The latter needs
to pay for entering the queue, as otherwise we do not exert backpressure.

This patch differentiates the two code paths, so they behave as they
should. Also add more debug information in timer paths.

Change-Id: I609be2332b13868ef1b9511399e2827d7f3d5b7d
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>
(cherry picked from commit 851fb56fba015c9fee3f0f9235c5c631a492ce59)