samples: tracing: remove USB backend configuration for testing format

Not all the hooks for k_events, k_lifo, k_fifo, k_msgq, and k_queue are
implemented in tracing_test.h and tracing_test.c and therefore the
testing format cannot be used with the new USB device stack.

Signed-off-by: Johann Fischer <johann.fischer@nordicsemi.no>

Author: jfischer-no

samples/subsys/tracing/README.rst

@@ -44,15 +44,6 @@ Usage for USB Tracing Backend
 
 Build a USB-tracing image with:
 
-.. zephyr-app-commands::
-	:zephyr-app: samples/subsys/tracing
-	:board: sam_e70_xplained/same70q21
-	:conf: "prj_usb.conf"
-	:goals: build
-	:compact:
-
-or:
-
 .. zephyr-app-commands::
 	:zephyr-app: samples/subsys/tracing
 	:board: sam_e70_xplained/same70q21

samples/subsys/tracing/prj_usb.conf

@@ -44,10 +44,6 @@ tests:
       - qemu_x86
     extra_args: CONF_FILE="prj_uart.conf"
     filter: dt_chosen_enabled("zephyr,tracing-uart")
-  sample.tracing.transport.usb:
-    platform_allow: sam_e70_xplained/same70q21
-    depends_on: usb_device
-    extra_args: CONF_FILE="prj_usb.conf"
   sample.tracing.transport.uart.ctf:
     platform_allow:
       - qemu_x86