test: verify Polkadot AH USDT sync too, not just Pezkuwi's own chains (#47)

The FullSyncPaymentUpdater ordering-bug fix isn't Pezkuwi-specific - it
affects any chain's assets on a busy shared subscription connection.
'USDT on Polkadot Asset Hub not showing' was one of the 3 original
symptoms reported at the start of this investigation, alongside Tron
being disabled and Pezkuwi's own tokens missing. Add it to the fixture
so the fix's coverage is actually verified end to end, not assumed.

pezkuwi-overlay/tests/pezkuwi_assets_for_testBalance.json

@@ -32,6 +32,13 @@
       "chainName": "Pezkuwi People",
       "assetId": 0,
       "symbol": "HEZ"
+    },
+    {
+      "chainId": "68d56f15f85d3136970ec16946040bc1752654e906147f7e43e9d539d7c3de2f",
+      "chainName": "Polkadot Asset Hub",
+      "assetId": 1,
+      "symbol": "USDT",
+      "note": "Non-Pezkuwi chain, deliberately included: 'USDT on Polkadot AH not showing' was one of the 3 originally reported symptoms this whole investigation started from. The fix (reverting FullSyncPaymentUpdater's ordering bug) isn't Pezkuwi-specific, so this verifies it actually closes that report too, not just the Pezkuwi chains."
     }
   ]
 }

tests/pezkuwi_assets_for_testBalance.json

@@ -32,6 +32,13 @@
       "chainName": "Pezkuwi People",
       "assetId": 0,
       "symbol": "HEZ"
+    },
+    {
+      "chainId": "68d56f15f85d3136970ec16946040bc1752654e906147f7e43e9d539d7c3de2f",
+      "chainName": "Polkadot Asset Hub",
+      "assetId": 1,
+      "symbol": "USDT",
+      "note": "Non-Pezkuwi chain, deliberately included: 'USDT on Polkadot AH not showing' was one of the 3 originally reported symptoms this whole investigation started from. The fix (reverting FullSyncPaymentUpdater's ordering bug) isn't Pezkuwi-specific, so this verifies it actually closes that report too, not just the Pezkuwi chains."
     }
   ]
 }