* Remove chain ops replace in go.mod

* Add waitForL1OriginOnL2 helper function

This makes it easier to wait for system config changes or deposits
to be included on L2.

* Add TestGasPriceOracleFeeUpdates

This test was initially written by Trail of Bits. I have modified
it to remove some helper functions & work with the new gas price
oracle configuration method (derived from L1 instead of L2).

* Add TestL2SequencerRPCDepositTx

This test was originally written by Trail of Bits. I modified it
to not use helper functions and work with the updated system.

* Add TestMixedDepositValidity

This test was originaly written by Trail of Bits. I modified the test to make
it work with the updated system & modified several components of the system
to make this test work. The largest change is now the premine is applied to
L2 in addition to L1.

* Add TestMixedWithdrawalValidity

This test was originally written by Trail of Bits. This modifies the test to
work with the new system.

* CI: Increase timeout for e2e tests

* CI: Enable parallel e2e tests again

The tests are stable enough & taking long enough without this flag that I think
it is worth making the tests parallel. We still have the option to run the
tests sequentially if we need the better output for debugging them.

* op-e2e: Increase timeout while waiting for withdrawal to finalize

* Address PR comments