pytest: fix race in test_zeroconf_forget

fundwallet() actually mines a block, putting our count out.  If we see
both blocks at once, we will say "52" blocks instead of "51":

```
2025-05-02T05:28:40.5315155Z         have_forgotten = l2.daemon.is_in_log(
2025-05-02T05:28:40.5315650Z             r"UNUSUAL {}-chan#1: Forgetting channel: It has been 51 blocks without the funding transaction ".format(l1.info['id'])
2025-05-02T05:28:40.5316105Z         )
2025-05-02T05:28:40.5316263Z     
2025-05-02T05:28:40.5316417Z         if dopay:
2025-05-02T05:28:40.5316616Z             assert not have_forgotten
2025-05-02T05:28:40.5317056Z             assert set([c['peer_id'] for c in l2.rpc.listpeerchannels()["channels"]]) == set([l1.info['id'], l3.info['id']])
2025-05-02T05:28:40.5317477Z         else:
2025-05-02T05:28:40.5317662Z >           assert have_forgotten
2025-05-02T05:28:40.5317887Z E           assert None
```

```
0266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c03518-chan#1: Forgetting channel: It has been 52 blocks without the funding transaction 0bb0579df6b1d983dda49dad47513afc71696c9d5bea3c8b955ba4b76bb053de getting deeply confirmed. We are fundee and can forget channel without loss of funds.
```

Signed-off-by: Rusty Russell <[email protected]>

Author: rustyrussell

tests/test_opening.py

@@ -2718,8 +2718,10 @@ def censoring_sendrawtx(tx):
 
     l1.daemon.rpcproxy.mock_rpc("sendrawtransaction", censoring_sendrawtx)
 
-    l1.connect(l2)
     l1.fundwallet(10**7)
+    l3.fundwallet(10**7)
+
+    l1.connect(l2)
     l1.rpc.fundchannel(l2.info["id"], 10**6, mindepth=0)
     sync_blockheight(bitcoind, [l1, l2])
     wait_for(lambda: l2.rpc.listincoming()["incoming"] != [])
@@ -2736,7 +2738,6 @@ def censoring_sendrawtx(tx):
 
     # We need *another* channel to make it forget the first though!
     l3.connect(l2)
-    l3.fundwallet(10**7)
     l3.rpc.fundchannel(l2.info["id"], 10**6, mindepth=0)
     bitcoind.generate_block(1)