Investigate Paymaster tracker op rejection

[0xfourzerofour]

Describe the bug

There is an intermittent error on the paymaster tracker that will return a PaymasterBalanceToLow error when new ops are added to the pool. I believe this is due to a large number of ops using the same paymaster that are pending in the pool leading to the new operations being rejected due to the pending balance (This is the correct way it should be) however we need to double check the calculation and make sure it is not something else.