Hide/remove settlement price and feed price from exchange page for bitCNY and other committee-controlled assets

**Is your feature request related to a problem? Please describe.**
Due to [BSIP42](https://github.com/bitshares/bsips/blob/master/bsip-0042.md), witnesses are feeding adjusted price for at least bitCNY. The result is good so far, according to https://coinmarketcap.com/currencies/bitcny/, bitCNY is now trading almost at par.


However, a side effect is the settlement price showing on the exchange page is a bit far away from current trading price, thus quite some users got confused, especially who have got used to that settlement price was always same as trading price on external exchanges. Actually, now, the latest trading price is the best source to check how much the BTS token is being traded at.

https://wallet.bitshares.org/#/market/BTS_CNY

https://coinmarketcap.com/currencies/bitshares/#markets

**Describe the solution you'd like**
Here I propose that we hide/remove the settlement price and feed price from exchange page, at least for affected assets. Personally I think all committee-controlled smart coins are affected or will be affected, but not only bitCNY.

**Describe alternatives you've considered**

**Additional context**

Locate the exchange-page components that render settlement and feed prices, then inspect how bitCNY and other committee-controlled assets are identified. Confirm the behavior for affected assets and unrelated markets; done means the targeted prices are hidden or removed without altering other exchange information.

Written by the indexing model from the issue text.