Inconsistent defaults for PoS and Governance and Parameters

[mariari]

The default parameters for PosParams and GovParams disagrees with the default values set in dev.toml.

PoS parameters:

• max_validator_slots in particular

https://github.com/anoma/namada/blob/main/proof_of_stake/src/parameters.rs#L47

https://github.com/anoma/namada/blob/main/genesis/dev.toml#L155

Governance parameters:

• max_proposal_content_size in particular

https://github.com/anoma/namada/blob/main/core/src/ledger/governance/parameters.rs#L61

https://github.com/anoma/namada/blob/main/genesis/dev.toml#L190

[tzemanovic]

sry, the dev.toml is outdated as it's not being used - we're re-working the genesis setup in #685 and dev.toml will be replaced. I don't think that the "dev" local net setup necessarily has to use the defaults, although it would probably be nicer if it did