fix(sct_runner.py): use larger disk for long longevity
fix(sct_runner.py): use larger disk for long longevity

My 1TB-longevity failed in collecting logs because of ENOSPC on sct
runner. I know it's not a common case, but when it occurs we might lost
the test logs.

Signed-off-by: Amos Kong <eb01d8f828a6c9a20be4534e72e049aaf41503df@scylladb.com>

scylladb/scylla-cluster-tests,scylladb/scylla-longevity-tests,scylladb/scylla-cluster-tests,scylladb/scylla-longevity-tests,scylladb/scylla-cluster-tests,scylladb/scylla-longevity-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests