MINOR: http: Reorder/rewrite checks in http_resync_states

MINOR: http: Reorder/rewrite checks in http_resync_states

The previous patch removed the forced symmetry of the TUNNEL mode during the
state synchronization. Here, we take care to remove body analyzer only on the
channel in TUNNEL mode. In fact, today, this change has no effect because both
sides are switched in same time. But this way, with some changes, it will be
possible to keep body analyzer on a side (to finish the states synchronization)
with the other one in TUNNEL mode.

WARNING: This patch will be used to fix a bug. The fix will be commited in a
very next commit. So if the fix is backported, this one must be backported too.