Build: Remove redundant ST nightly config group

ST nightly config group is same as the common ST group.
Reuse the common ST group in nightly job is good enough.

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: Ib5323f0719909c7af4510fe6008f9d35af2e66e6
1 file changed