chore: update Mainnet Golden Week height (#13335)

```
2025-09-24T23:00:00Z
5348280
```

Author: TippyFlitsUK

build/buildconstants/params_mainnet.go

@@ -138,8 +138,8 @@ var UpgradeTockHeight = UpgradeTeepHeight + builtin.EpochsInDay*90
 // Only applied to calibnet which was already upgraded to Teep&Tock
 var UpgradeTockFixHeight = abi.ChainEpoch(-1)
 
-// ??????
-var UpgradeGoldenWeekHeight = abi.ChainEpoch(9999999999)
+// 2025-09-24T23:00:00Z
+var UpgradeGoldenWeekHeight = abi.ChainEpoch(5348280)
 
 var UpgradeTeepInitialFilReserved = InitialFilReserved // FIP-0100: no change for mainnet