Conversion state is dumped too frequently

[sug0]

The conversion state is being written to rocksdb at every epoch. However, in practice, it is only updated at every masp epoch, which is a multiple of a regular epoch. This means that we are writing the same data to storage multiple times.

https://github.com/anoma/namada/blob/c465b7d4f41409ef439649e5509386c92be4fa59/crates/node/src/storage/rocksdb.rs#L1301-L1309

[grarco]

Actually it seems like we call add_block_to_batch only once and we provide a true value for is_full_commit, so I'm not even sure we need that argument at all