Prop 429: Remove Exit Fee option from pools

Passing this proposal indicates that the Exit Fee option should be removed from all new and existing pools in a future software upgrade.

## Details
Exit fees are an option that can be enabled at the point of pool creation. These cause Liquidity Providers to pay a fee when withdrawing from the pool. Users withdraw their tokens, minus a proportion of the LP shares, for the exit fee. These LP shares are burned, resulting in pro-rata distribution to remaining LPs.

As a method of retaining liquidity their usefulness is questionable. A liquidity provider who wishes to leave the pool will likely regard a small 0.1% fee as negligible compared to their reasoning for leaving, such as migration to another pool or confirming their current ratio of assets.

A larger fee may be better at retaining liquidity, however, these begin to prevent users from leaving the pool without sacrificing earned rewards and therefore increase the hurdle for users to overcome the sunk cost fallacy on declining pools.

Currently there is no display of the exit fee on the Osmosis.zone frontend and so a user may not be aware of this fee when joining a pool, therefore being unable to estimate the time they must provide liquidity for before their returns outweigh the exit fee. If this proposal is rejected then this should be added to make users aware of potential exit fees on pools.

Very few pools have utilised exit fees during the lifetime of Osmosis, the majority of which are abandoned. All pools currently utilising Exit fees are listed below.

This proposal argues that the option to have exit fees is at best, obsolete, with other methods of liquidity stickiness such as the now default 14 day bonding time, and at worst harmful to the Osmosis liquidity provision experience. Accommodating this setting in frontend displays and integrations causes unnecessary complexity and so this setting should be removed during a future software upgrade.

During removal, all pools with Exit Fee settings will have it removed and no future pools will be able to add one.

## Affected pools
553 - LIKE/OSMO
596 - BOOT/ATOM
555 - LIKE/ATOM
905 - DYS/OSMO
597 - BOOT/OSMO
802 - ATOM/stATOM
654 - CRBRUS/HUAHUA
595 - BOOT/ATOM
696 - GLX/OSMO
551 - LIKE/OSMO
552 - LIKE/ATOM
554 - LIKE/ATOM
652 - CRBRUS/OSMO
655 - CRBRUS/HUAHUA
657 - CRBRUS/HUAHUA
797 - UMEE/HOPE

Including Liquidity and Exit Fee settings

Commonwealth Thread: https://commonwealth.im/osmosis/discussion/9793-remove-exit-fee-option-from-pools