.gitlab-ci: Disable toolchains
meta-zephyr's CI doesn't use them so far and it causes yaml merging
issues
Signed-off-by: 
Pavel Zhukov <pavel.zhukov@huawei.com>
meta-zephyr's CI doesn't use them so far and it causes yaml merging
issues
Signed-off-by: Pavel Zhukov <pavel.zhukov@huawei.com>