fix(txpool): missing condition that tx gas limit equal to block gas l…

[hsyodyssey]

I found the following issue when I was doing a one block one transaction test (for benchmarking).

In short, the insert transaction function does not mark a transaction as TxState::NOT_TOO_MUCH_GAS when its gas limit is equal to the Block gas limit.

• I tried on Geth to do a test and found that this kind of transaction seems to be legal since the constraint is only not to exceed the Block Gas Limit, test here
• I found that the ensure_valid function already handles the case where the transaction's gas limit is greater than the block's gas limit. Therefore, passing through ensure_valid transactions could be all be marked as TxState::NOT_TOO_MUCH_GAS.
• It also make the logic for the evaluation here seemed a bit redundant, so I made some modifications and added a new unit test.

[rkrasiuk]

@mattsse do we need this state flag at all?

[mattsse]

thanks, this check was indeed redundant because already checked in ensure_valid.

perhaps we don't even need the state flag at all and we should consider removing that