Testsuite - Fix tes7.9 precondition to cray_aries

Bug 7621

testsuite/expect/test7.9

@@ -54,25 +54,8 @@ if {![test_accting_steps]} {
 # Each leave open files, although we could clear the proctrack related files
 # by just closing all files after fd=3.
 #
-set invalid 0
-log_user 0
-spawn $scontrol show config
-expect {
-	-re "proctrack/cray" {
-		send_user "\nWARNING: test incompatible with proctrack/cray\n"
-		set invalid 1
-		exp_continue
-	}
-	timeout {
-		send_user "\nFAILURE: scontrol not responding\n"
-		set exit_code 1
-	}
-	eof {
-		wait
-	}
-}
-log_user 1
-if {$invalid == 1} {
+if {[string compare [test_proctrack] "cray_aries"] == 0} {
+	log_warn "Test incompatible with proctrack/cray_aries"
 	exit $exit_code
 }