Define SSHCONF from strongswan testing directory, not TESTDIR

This fixes the use of SSHCONF in the ssh wrapper script before ./do-tests
had a chance to create the required symlinks.

testing/testing.conf

@@ -65,9 +65,6 @@ KVMGROUP=kvm
 # Directory where test results will be stored
 TESTRESULTSDIR=$TESTDIR/testresults
 
-# SSH configuration (speedup SSH)
-SSHCONF="-F $TESTDIR/testing/ssh_config"
-
 ##############################################################
 # Enable particular steps in the make-testing
 #