Increase the x/gov MsgSubmitProposal cost and don't delete dead proposals.

[robert-zaremba]

Summary

Currently proposals which are inactive (still in deposit phase) and didn't get into active queue (voting phase) are deleted and the deposit is burned. Let's call the deleted inactive proposals as ghost.

ref: #9519 (comment)

Problem Definition

• Ghost proposals are note queryable - it's fine - when a inactive proposal is deleted we emit an InactiveProposal event with AttributeValueProposalDropped attribute. No need to spam the network
• however, the inactive proposals are queried during all blocks (x/gov EndBlocker) and nobody is paying for that

Proposal

Increase a cost of MsgSubmitProposal to pay for the future query in EndBlocker. We don't need to make it expensive. Consuming extra gas should be sufficient: x * storage_byte_cost * proposal_bytes_size , where x is something like 3-5.

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[robert-zaremba]

@alexanderbez - in fact I've changed my mind - we can remove the inactive proposals because we have events for them (but don't have a strong opinion here, we can keep them as well). However argument to make the transaction more expensive stays - so I propose to increase the consumed gas in MsgSubmitProposal.

@aaronc , @clevinson - I've added it to 0.44, if we only increase the gas then it's very easy and don't break the UX.

[alexanderbez]

If we also remove inactive proposals, we don't iterate over them in x/gov EndBlock, right? If that's the case, what is the argument for making those txs more expensive (not saying I'm against it)?

[robert-zaremba]

We remove inactive proposals in x/gov End Block (when iterating over inactive proposals queue).

[alexanderbez]

ACK on the proposal. Another approach is to have a minimum self-deposit (param) when submitting a MsgSubmitProposal message.