boards: m5stack: m5stack_fire is not a default test platform

remove testing default=true from this board as it is not a default test
platform

(cherry picked from commit c576464)

Original-Signed-off-by: Benjamin Cabé <[email protected]>
GitOrigin-RevId: c576464
Cr-Build-Id: 8712973260362085153
Cr-Build-Url: https://cr-buildbucket.appspot.com/build/8712973260362085153
Copybot-Job-Name: zephyr-main-copybot-downstream
Change-Id: Ia307106dbc102fe8d6032ef037353904fd94083c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/6621875
Commit-Queue: Dawid Niedźwiecki <[email protected]>
Reviewed-by: Dawid Niedźwiecki <[email protected]>
Tested-by: Dawid Niedźwiecki <[email protected]>
Tested-by: ChromeOS Copybot <[email protected]>

Author: Benjamin Cabé

boards/m5stack/m5stack_fire/m5stack_fire_procpu.yaml

@@ -14,5 +14,3 @@ supported:
   - nvs
   - pwm
 vendor: m5stack
-testing:
-  default: true