[thci] increase BBR Sequence Number when dataset changes (#7558)

Make sure BBR Sequence Number is increased when Re-registration
Delay or MLR Timeout changes.

tools/harness-thci/OpenThread.py

@@ -2963,6 +2963,11 @@ class OpenThreadTHCI(object):
             False: fail to set BBR Dataset
         """
         assert not (SeqNumInc and SeqNum is not None), "Must not specify both SeqNumInc and SeqNum"
+
+        if (MlrTimeout and MlrTimeout != self.bbrMlrTimeout) or (ReRegDelay and ReRegDelay != self.bbrReRegDelay):
+            if SeqNum is None:
+                SeqNumInc = True
+
         if SeqNumInc:
             if self.bbrSeqNum in (126, 127):
                 self.bbrSeqNum = 0
@@ -2970,6 +2975,8 @@ class OpenThreadTHCI(object):
                 self.bbrSeqNum = 128
             else:
                 self.bbrSeqNum = (self.bbrSeqNum + 1) % 256
+        else:
+            self.bbrSeqNum = SeqNum
 
         return self.__configBbrDataset(SeqNum=self.bbrSeqNum, MlrTimeout=MlrTimeout, ReRegDelay=ReRegDelay)
 
@@ -3256,7 +3263,7 @@ class OpenThreadTHCI(object):
     @API
     def setMLRtimeout(self, iMsecs):
         """Setup BBR MLR Timeout to `iMsecs` seconds."""
-        self.__configBbrDataset(MlrTimeout=iMsecs)
+        self.setBbrDataset(MlrTimeout=iMsecs)
 
     @API
     def stopListeningToAddr(self, sAddr):