Remove the priority scheudler

As I'm not sure it's helping.

guix-data-service/web/server.scm

@@ -112,37 +112,9 @@
     #:unwind? #t)
 
   (let ((finished?         (make-condition))
-        (priority-scheduler #f)
         (request-scheduler #f))
     (call-with-sigint
      (lambda ()
-       (call-with-new-thread
-        (lambda ()
-          (run-fibers
-           (lambda ()
-             (let* ((current (current-scheduler))
-                    (schedulers
-                     (cons current (scheduler-remote-peers current))))
-
-               (set! priority-scheduler current)
-
-               (for-each
-                (lambda (i sched)
-                  (spawn-fiber
-                   (lambda ()
-                     (catch 'system-error
-                       (lambda ()
-                         (set-thread-name
-                          (string-append "priority " (number->string i))))
-                       (const #t)))
-                   sched))
-                (iota (length schedulers))
-                schedulers))
-
-             (wait finished?))
-           #:hz 0
-           #:parallelism 1)))
-
        (run-fibers
         (lambda ()
           (let* ((current (current-scheduler))
@@ -161,9 +133,6 @@
              (iota (length schedulers))
              schedulers))
 
-          (while (not priority-scheduler)
-            (sleep 0.1))
-
           (let ((requests-metric
                  (make-counter-metric registry "requests_total")))
 
@@ -191,8 +160,7 @@ port. Also, the port used can be changed by passing the --port option.\n"
                        #:idle-seconds 5
                        #:destructor
                        (lambda (conn)
-                         (close-postgresql-connection conn "background"))
+                         (close-postgresql-connection conn "background"))))
-                       #:scheduler priority-scheduler))
 
                      (connection-pool
                       (make-resource-pool
@@ -208,8 +176,7 @@ port. Also, the port used can be changed by passing the --port option.\n"
                          (close-postgresql-connection conn "web"))
                        #:default-max-waiters (floor (/ postgresql-connections 2))
                        #:default-checkout-timeout (/ postgresql-statement-timeout
-                                                     1000)
+                                                     1000)))
-                       #:scheduler priority-scheduler))
 
                      (reserved-connection-pool
                       (make-resource-pool
@@ -224,8 +191,7 @@ port. Also, the port used can be changed by passing the --port option.\n"
                        (lambda (conn)
                          (close-postgresql-connection conn "web-reserved"))
                        #:default-max-waiters postgresql-connections
-                       #:default-checkout-timeout 6
+                       #:default-checkout-timeout 6)))
-                       #:scheduler priority-scheduler)))
 
                   (let ((resource-pool-checkout-failures-metric
                          (make-counter-metric registry