Test: cts: Drop -S option from cts script.

Don't summarize log files from ~/CTS-*/cluster-log.txt.

The "-S" option was documented as "show summary from the last CTS run."

Nothing in the cts script creates anything in "~/CTS-*" directories nor
even creates those directories. There's no reason for them to exist
unless the user reads this script, creates them manually, and stores old
cts-lab run logs there. Further, it looks as if this has always been the
case.

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>