hydra: bayfront: Make some guix-build-coordinator hook tweaks.

* hydra/bayfront.scm (%guix-build-coordinator-configuration): Support
more parallel build-success hooks and make the build-missing-inputs
hook do nothing, as this should be unused.

hydra/bayfront.scm

@@ -862,9 +862,12 @@ proxy_set_header  Via  $via;"
       '((build-submitted . 6)
         (build-canceled . 6)
         (build-started . 6)
-        (build-success . 4)))
+        (build-success . 24)))
      (hooks
-      `((build-submitted
+      `((build-missing-inputs
+         ;; Builds shouldn't be missing inputs, so disable this hook
+         . ,#~(const #t))
+        (build-submitted
          . ,#~(lambda args
                 #$(send-guix-data-service-event
                    'build-submitted-send-event-to-guix-data-service-hook)))