[Sequencer] 0 txn blocks created when transactions are available

[hexoscott]

we see a pattern in busier networks where the sequencer can occasionally build a block with 0 transactions when there is data in the pool available. The strange pattern is that these are always followed by a 0s block that does contain transactions like the example below:

We need to figure out why this is happening and ensure there are no 0 txn blocks and no 0s blocks

[hexoscott]

Target fix in #1525