BUG/MEDIUM: peers: fix expire date wasn't updated if entry is modified remotely.

BUG/MEDIUM: peers: fix expire date wasn't updated if entry is modified remotely.

The stktable_touch_remote considers the expire field stored in the stksess
struct.
The expire field was updated on the a newly created stksess to store.

But if the stksess with a same key is still present the expire was not updated.

This patch postpones the update of the expire field of the stksess just before
processing the "touch".

These bug was introduced in commit:

MEDIUM: threads/stick-tables: handle multithreads on stick tables.

And the fix should be backported on 1.8.