Fix incorrect mocktime set in [no] miner fund test

Summary:
`node.setmocktime()` is called but the node is restarted immediately after.
Move setting the mock time to after the node starts back up since it's restarted many
times in this test.

Test Plan: `test_runner.py bchn-no-miner-fund-activation.py`

Reviewers: #bitcoin_abc, nakihito, Fabien

Reviewed By: #bitcoin_abc, nakihito, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D6090

test/functional/bchn-no-miner-fund-activation.py

@@ -69,7 +69,6 @@ def check_all_bip9_state(status):
         def run_test_for(bit, name, address):
             # Make sure we have a clean slate.
             node.invalidateblock(node.getblockhash(height + 1))
-            node.setmocktime(1580000000)
             self.run_miner_fund_test(bit, name, address)
 
         run_test_for(0, 'minerfund', MINER_FUND_ADDR)
@@ -118,6 +117,7 @@ def run_miner_fund_test(self, bit, name, fund_address):
                         ["-blockversion={}".format(version), "-phononactivationtime={}".format(PHONON_ACTIVATION_TIME)])
 
         node = self.nodes[0]
+        node.setmocktime(1580000000)
         address = node.get_deterministic_priv_key().address
 
         def get_best_vote():