Max bundle body size regression

[rileyg98]

Hi team,

I've noticed that the max bundle size in https://github.com/flashbots/mev-share-node/blob/main/mevshare/mevshare.go#L21 is 50 - this introduces a regression in the main relay endpoint where a bundle that would succeed through the standard eth_sendBundle JSON-RPC call fails when sent via the mev_sendBundle endpoint - including where a proxy reformats requests from eth_sendBundle (in the case of a bundle including a list of builders for secondary transmission, as per https://docs.flashbots.net/flashbots-auction/advanced/rpc-endpoint#eth_sendbundle) to mev_sendBundle. This limit is also not specified anywhere in documentation.

Is there any particular reason for the limit of 50 transactions? Bundles these size are used regularly in the altcoin community during contract launches.