Currently, the session ID under which the truncate for tablets request is
running is created during the request creation and queuing. This is a problem
because this could overwrite the session ID of any ongoing operation on
system.topology#session
This change moves the creation of the session ID for truncate from the request
creation to the request handling.
Fixes#22613Closesscylladb/scylladb#22615
(cherry picked from commit a59618e83d)
Closesscylladb/scylladb#22705