allscenarios-linux.conf: Revert enable optee in distribution"

The optee DISTRO_FEATURE seems to only be used in
https://github.com/STMicroelectronics/meta-st-openstlinux

 which we don't
pull in our setup as of now. Drop this change to avoid confusion.

This reverts commit 229e09c3.

Signed-off-by: Andrei Gherzan <andrei.gherzan@huawei.com>