[sequencer] in-depth testing on Sepolia

[jonastheis]

In our efforts to make sure that RN+reth sequencer is sound, safe and efficient/performant we should do some repeated load and stress tests.

These tests should include:

• spamming of L1 messages and enforced transactions
• fuzz tests
• high load tests/benchmarks (test what is the maximum mgas/seconds limit that can be sustained)

Preferably, all of the above mentioned can be performed together (ie in a single test) and repeated 2-3 times to make sure results are consistent.

We should then evaluate whether the sequencer produced correct blocks and the load it can sustain. Similarly, for RN follower nodes we should check their performance.