frr: T6746: add guard time after commit() and before getFRRconfig()

As vyos-configd will take care about the commit via FRRender class, and FRR
needs to internally process the configuration we might read it back via
vtysh "to fast". Add a 5 seconds guard timer after each commit() and
before calling getFRRconfig().

Guard timer is reset with each commit().

smoketest/scripts/cli/base_vyostest_shim.py

@@ -18,6 +18,7 @@
 import pprint
 
 from time import sleep
+from time import time
 from typing import Type
 
 from vyos.configsession import ConfigSession
@@ -43,7 +44,7 @@ class TestCase(unittest.TestCase):
         # trigger the certain failure condition.
         # Use "self.debug = True" in derived classes setUp() method
         debug = False
-
+        commit_guard = 0
         @classmethod
         def setUpClass(cls):
             cls._session = ConfigSession(os.getpid())
@@ -81,6 +82,7 @@ def cli_discard(self):
             self._session.discard()
 
         def cli_commit(self):
+            self.commit_guard = time()
             if self.debug:
                 print('commit')
             self._session.commit()
@@ -104,8 +106,9 @@ def op_mode(self, path : list) -> None:
         def getFRRconfig(self, string=None, end='$', endsection='^!', daemon=''):
             """ Retrieve current "running configuration" from FRR """
             # Sometimes FRR needs some time after reloading the configuration to
-            # appear in vtysh. This is a workaround addiung a 2 seconds guard timer
-            sleep(2)
+            # appear in vtysh. This is a workaround addiung a 5 seconds guard timer
+            while time() - self.commit_guard < 5:
+                sleep(0.250)
             command = f'vtysh -c "show run {daemon} no-header"'
             if string: command += f' | sed -n "/^{string}{end}/,/{endsection}/p"'
             out = cmd(command)