fix: intermittent failure in feature_llmq_simplepose.py (#5859)

## Issue being fixed or feature implemented
kudos to kwvg to report issue: he pointed out that functional tests
randomly fail lately.
Bisect pointed out an exact commit: bitcoin#20027 - mockable time
everywhere

## What was done?
Added call `mn.node.mockscheduler` as it is done in 20027 for other
functional tests

## How Has This Been Tested?
Run 20 times. Without this patch 20% failures; with this patch - zero
failures.
```
test/functional/test_runner.py -j20 feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py feature_llmq_simplepose.py
```

## Breaking Changes
N/a

## Checklist:
- [x] I have performed a self-review of my own code
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] I have added or updated relevant unit/integration/functional/e2e
tests
- [ ] I have made corresponding changes to the documentation
- [x] I have assigned this pull request to a milestone

---------

Co-authored-by: UdjinM6 <UdjinM6@users.noreply.github.com>

test/functional/feature_llmq_simplepose.py

@@ -189,21 +189,24 @@ def repair_masternodes(self, restart):
                 addr = self.nodes[0].getnewaddress()
                 self.nodes[0].sendtoaddress(addr, 0.1)
                 self.nodes[0].protx('update_service', mn.proTxHash, '127.0.0.1:%d' % p2p_port(mn.node.index), mn.keyOperator, "", addr)
-                # Make sure this tx "safe" to mine even when InstantSend and ChainLocks are no longer functional
-                self.bump_mocktime(60 * 10 + 1)
-                self.nodes[0].generate(1)
-                assert not self.check_banned(mn)
-
                 if restart:
                     self.stop_node(mn.node.index)
                     self.start_masternode(mn)
                 else:
                     mn.node.setnetworkactive(True)
             self.connect_nodes(mn.node.index, 0)
+
+        # syncing blocks only since node 0 has txes waiting to be mined
+        self.sync_blocks()
+
+        # Make sure protxes are "safe" to mine even when InstantSend and ChainLocks are no longer functional
+        self.bump_mocktime(60 * 10 + 1)
+        self.nodes[0].generate(1)
         self.sync_all()
 
         # Isolate and re-connect all MNs (otherwise there might be open connections with no MNAUTH for MNs which were banned before)
         for mn in self.mninfo:
+            assert not self.check_banned(mn)
             mn.node.setnetworkactive(False)
             self.wait_until(lambda: mn.node.getconnectioncount() == 0)
             mn.node.setnetworkactive(True)