refactor(ras): rename ras related tests

RAS related tests implicitly use SError name and as there are plans to
introduce non-RAS SError test, rename RAS related tests to be explicit.

Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: Ifc56157271e491e1b7c5eeac7b0e1e08bf138b8f