CA-384148 remove lock in Redo_log.startup

The lock is circular:

  startup: lock -> broken -> shutdown : lock

Signed-off-by: Christian Lindig <christian.lindig@cloud.com>

Author: Christian Lindig

ocaml/database/redo_log.ml

@@ -626,7 +626,6 @@ let healthy log =
 exception TooManyProcesses
 
 let startup log =
-  with_lock log.mutex @@ fun () ->
   if is_enabled log then (
     try
       ( match !(log.pid) with