sanitycheck miss extra_args: OVERLAY_CONFIG parameter

[finikorg]

Describe the bug
We have several sample.yaml for example in samples/net/zperf/ with following overlay configuration:

  test_netusb_ecm:
    extra_args: OVERLAY_CONFIG="overlay-netusb.conf"
    extra_configs:
      - CONFIG_NET_TCP=n
      - CONFIG_SHELL_CMDS=n
    tags: usb net zperf
    depends_on: usb_device

For some reason sanitycheck misses all configuration from overlay files.

To Reproduce
Steps to reproduce the behavior:

sanitycheck -t zperf

Expected behavior
Should check with overlay config included

Impact
Does not test overlays