nixos/test/virtualbox: Fix linting errors

There were a bunch of unnecessary f-strings in there and I also removed
the "# fmt: on/off" comments, because we no longer use Black and thus
won't need those comments anymore.

Signed-off-by: aszlig <aszlig@nix.build>

nixos/tests/virtualbox.nix

@@ -226,18 +226,16 @@ let
 
 
       def create_vm_${name}():
-          # fmt: off
-          vbm(f"createvm --name ${name} ${createFlags}")
-          vbm(f"modifyvm ${name} ${vmFlags}")
-          vbm(f"setextradata ${name} VBoxInternal/PDM/HaltOnReset 1")
-          vbm(f"storagectl ${name} ${controllerFlags}")
-          vbm(f"storageattach ${name} ${diskFlags}")
-          vbm(f"sharedfolder add ${name} ${sharedFlags}")
-          vbm(f"sharedfolder add ${name} ${nixstoreFlags}")
+          vbm("createvm --name ${name} ${createFlags}")
+          vbm("modifyvm ${name} ${vmFlags}")
+          vbm("setextradata ${name} VBoxInternal/PDM/HaltOnReset 1")
+          vbm("storagectl ${name} ${controllerFlags}")
+          vbm("storageattach ${name} ${diskFlags}")
+          vbm("sharedfolder add ${name} ${sharedFlags}")
+          vbm("sharedfolder add ${name} ${nixstoreFlags}")
           cleanup_${name}()
 
           ${mkLog "$HOME/VirtualBox VMs/${name}/Logs/VBox.log" "HOST-${name}"}
-          # fmt: on
 
 
       def destroy_vm_${name}():
@@ -259,9 +257,7 @@ let
 
       def wait_for_ip_${name}(interface):
           property = f"/VirtualBox/GuestInfo/Net/{interface}/V4/IP"
-          # fmt: off
           getip = f"VBoxManage guestproperty get ${name} {property} | sed -n -e 's/^Value: //p'"
-          # fmt: on
 
           ip = machine.succeed(
               ru(
@@ -394,9 +390,7 @@ let
 
       machine.wait_for_x()
 
-      # fmt: off
       ${mkLog "$HOME/.config/VirtualBox/VBoxSVC.log" "HOST-SVC"}
-      # fmt: on
 
       ${testScript}
       # (keep black happy)