test/hil: fix esp32 audio_test_freertos (FreeRTOS tick), skip metro_m4

Enabling the audio test fleet-wide surfaced failures on esp32-p4/s3 and
metro_m4_express: the UAC mic enumerates but arecord fails the iso IN read
with EIO, while 18 other boards pass strict=1.000.

esp32: root cause is the FreeRTOS tick rate. ESP-IDF defaults
CONFIG_FREERTOS_HZ to 100, so the audio task wakes only every 10 ms and
can't service the 1 ms UAC iso frames -> underrun -> arecord EIO. (The same
dwc2 driver passes on STM32, whose FreeRTOSConfig is 1000 Hz.) Set
CONFIG_FREERTOS_HZ=1000 in the example sdkconfig.defaults; the example
defaults are honored in the generated sdkconfig alongside the BSP's, so this
takes effect.

metro_m4_express (samd51): not tick-rate -- its FreeRTOSConfig is already
1000 Hz like the passing boards -- so it's a separate iso-IN issue, skipped
for now.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

test/hil/tinyusb.json

@@ -132,6 +132,7 @@
                 "device": true,
                 "host": false,
                 "dual": true,
+                "skip": ["device/audio_test_freertos"],
                 "dev_attached": [
                     {
                         "vid_pid": "067b_2303",
@@ -139,7 +140,7 @@
                         "is_cdc": true
                     }
                 ],
-                "comment": "pl23x"
+                "comment": "pl23x; audio_test_freertos skipped: samd51 iso-IN capture fails (arecord EIO)"
             },
             "flasher": {
                 "name": "jlink",