Increase the Deposit Pool limit

This proposal is to increase the deposit pool limit to 5,000 ETH from the current setting of 2,000 ETH.

Increasing the deposit pool limit will allow for more efficient and larger deposits by Institutional, DAO, and private whale depositors into the deposit pool.

Increasing the deposit pool limit does present a small potential reduction risk on the rETH APR but only occurs when the deposit pool has a positive balance. For further calculation on the impact please refer to the attached proposal.

https://github.com/rocket-pool/RPIPs/blob/main/RPIPs/RPIP-9.md