examples/tests/gdbtest.py: avoid using runtime variables in the test

The reason is that runtime GDB settings are set by the GDB plugin, and
when running the test in standalone mode, there's no plugin activation
whatsoever.
Signed-off-by: NCleber Rosa <crosa@redhat.com>

examples/tests/gdbtest.py

@@ -4,7 +4,6 @@ import os
 
 from avocado import test
 from avocado import gdb
-from avocado import runtime
 from avocado import job
 from avocado.utils import process
 
@@ -355,7 +354,7 @@ class GdbTest(test.Test):
         self.assertIn(listening_line, stderr_lines)
 
     def test_server_stderr_redirected(self):
-        s = gdb.GDBServer(runtime.GDBSERVER_PATH)
+        s = gdb.GDBServer()
         if not s.redirected_stderr:
             s.exit()
             return