Stop using bdwidth while printing, work without it

bdwidth's motion reading stays at 0, its per-reading width compensation
made the flow jump between 77 and 119%, and a USB dropout shut down
Klipper. PRINT_START no longer enables it. _PRINT_CLEANUP,
BLOBIFIER_CHECKED and PURGE_UNTIL_EMPTY only send bdwidth commands when
[bdwidth fila_width_0] exists, and bdwidth_status reports present: False
with neutral values when it is not configured, so the section can be
removed from printer.cfg.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

macros/afc/purge_check.cfg

@@ -65,13 +65,14 @@ gcode:
     # pause the printer (the check reports it instead). Afterwards the
     # runout response is restored; bdwidth itself is only switched off
     # again outside a print, so a print never loses it.
-    {% set bdw_on = cfg.motion_check and not printer.bdwidth_status.reading|default(false) %}
+    {% set has_bdw = printer.bdwidth_status.present|default(true) %}
+    {% set bdw_on = has_bdw and cfg.motion_check and not printer.bdwidth_status.reading|default(false) %}
     {% set bdw_off = bdw_on and printer.print_stats.state not in ["printing", "paused"] %}
     {% set runout_was = 1 if printer.bdwidth_status.enabled else 0 %}
     # Without the motion check, bdwidth's own runout response is off during
     # the purge too, so a bdwidth that does not see the movement cannot
     # pause the printer here; the pressure check judges the purge.
-    {% set runout_off = bdw_on or not cfg.motion_check %}
+    {% set runout_off = has_bdw and (bdw_on or not cfg.motion_check) %}
     {% if cfg.mode == "off" %}
         BLOBIFIER {rawparams}
     {% else %}