These tests had only ever been run on SVE or SVE+SME systems.
While investigating #138717 I found they failed on an SME only
system.
This happens because before the first stop we try to initialise
SVE registers while outside of streaming mode. Which causes a
SIGILL.
To fix this, require SVE to be present.
I could go in and make these work on SME only, but it's more
complex and I will be adding SME only specific tests in
future anyway.
f81444637c