Only strip /hookshot prefix for Hookshot widgetapi

Public URLs are like: `/hookshot/widgetapi/v1/static/`
.. which get translated to requests for: `/widgetapi/v1/static/`

Previously, we were stripping the whole `/hookshot/widgetapi` prefix,
which is wrong.

roles/custom/matrix-bridge-hookshot/defaults/main.yml

@@ -201,7 +201,6 @@ matrix_hookshot_widgets_roomSetupWidget_addOnInvite: false   # noqa var-naming
 #   - fec0::/10
 matrix_hookshot_widgets_disallowedIpRanges: ''   # noqa var-naming
 matrix_hookshot_widgets_internal: "/widgetapi"
-# Default value of matrix_hookshot_widgets_endpoint: "/hookshot/widgetapi"
 matrix_hookshot_widgets_hostname: "{{ matrix_hookshot_public_hostname }}"
 matrix_hookshot_widgets_endpoint: "{{ matrix_hookshot_public_endpoint }}{{ matrix_hookshot_widgets_internal }}"
 matrix_hookshot_widgets_publicUrl: "{{ matrix_hookshot_urlprefix }}{{ matrix_hookshot_widgets_endpoint }}/v1/static"   # noqa var-naming

roles/custom/matrix-bridge-hookshot/templates/labels.j2

@@ -83,7 +83,7 @@ traefik.http.routers.matrix-hookshot-appservice.tls.certResolver={{ matrix_hooks
 #                                                          #
 ############################################################
 
-traefik.http.middlewares.matrix-hookshot-widgets-strip-prefix.stripprefix.prefixes={{ matrix_hookshot_widgets_endpoint }}
+traefik.http.middlewares.matrix-hookshot-widgets-strip-prefix.stripprefix.prefixes={{ matrix_hookshot_public_endpoint }}
 
 traefik.http.routers.matrix-hookshot-widgets.rule={{ matrix_hookshot_container_labels_widgets_traefik_rule }}
 traefik.http.routers.matrix-hookshot-widgets.middlewares=matrix-hookshot-widgets-strip-prefix