cfg: Reserve tests.cfg to test runner

Point out in the main test cfg file used by the test
runner (tests.cfg) that we're not supposed to modify
its contents, since we apply extra cartesian line
parsing on top of it.

CC: Qingtang Zhou <qzhou@redhat.com>
Signed-off-by: NLucas Meneghel Rodrigues <lmr@redhat.com>

openvswitch/cfg/tests.cfg

-# Copy this file to tests.cfg and edit it.
-#
-# This file contains the test set definitions. Define your test sets here.
-
-# Include the base config files.
+# File reserved for test runner (./run) use, don't modify.
 include tests-shared.cfg
 
 kill_vm_only_when_paused = no

qemu/cfg/tests.cfg

-# Copy this file to tests.cfg and edit it.
-#
-# This file contains the test set definitions. Define your test sets here.
-
-# Include the base config files.
+# File reserved for test runner (./run) use, don't modify.
 include tests-shared.cfg
 
-# Here are the test sets variants
 variants:
-    # Runs qemu-kvm, JeOS 64 bit OS
     - @qemu_kvm_jeos_quick:
         qemu_binary = /usr/bin/qemu-kvm
         qemu_img_binary = /usr/bin/qemu-img
@@ -21,5 +15,4 @@ variants:
         only smallpages
         only JeOS.17.64
 
-# Choose your test list from the testsets defined
 only qemu_kvm_jeos_quick