Remove some unused state keys (#8776)

* Remove unused networkEndpointType state key

* Remove unused coinOptions state key

app/scripts/background.js

@@ -105,10 +105,8 @@ initialize().catch(log.error)
  * @property {Object} contractExchangeRates - Info about current token prices.
  * @property {Array} tokens - Tokens held by the current user, including their balances.
  * @property {Object} send - TODO: Document
- * @property {Object} coinOptions - TODO: Document
  * @property {boolean} useBlockie - Indicates preferred user identicon format. True for blockie, false for Jazzicon.
  * @property {Object} featureFlags - An object for optional feature flags.
- * @property {string} networkEndpointType - TODO: Document
  * @property {boolean} welcomeScreen - True if welcome screen should be shown.
  * @property {string} currentLocale - A locale string matching the user's preferred display language.
  * @property {Object} provider - The current selected network provider.

ui/app/ducks/metamask/metamask.js

@@ -31,10 +31,8 @@ export default function reduceMetamask (state = {}, action) {
       ensResolution: null,
       ensResolutionError: '',
     },
-    coinOptions: {},
     useBlockie: false,
     featureFlags: {},
-    networkEndpointType: undefined,
     welcomeScreenSeen: false,
     currentLocale: '',
     preferences: {