[ML] Index Data Visualizer url state error

[darnautov]

An error occurs on the Index Data Visualizer page when the URL state is trying to decode any URL parameters which aren't rison encoded, e.g. index or savedSearchId.
Presumably caused by the changes introduced in #52987.

backend.js:6 Could not read url state Error: rison decoder error: unable to parse string as rison: ''571aaf70-4c88-11e8-b3d7-01146121b73d''
    at rison.parser.errcb [as errorHandler] (rison.js:270)
    at rison.parser.parse (rison.js:333)
    at rison.decode (rison.js:275)
    at eval (url_state.ts:27)
    at Array.forEach (<anonymous>)
    at getUrlState (url_state.ts:26)
    at useUrlState (url_state.ts:90)
    at Tabs (tabs.tsx:75)
    at renderWithHooks (react-dom.development.js:16260)
    at updateFunctionComponent (react-dom.development.js:18347) 
    in Tabs (created by NavigationMenu)
    in NavigationMenu (created by Page)
    in Page (created by PageWrapper)
    in PageWrapper (created by Router.Consumer)
    in Router.Consumer (created by Route)
    in Route (created by MlRouter)
    in MlRouter (created by App)
    in App

[elasticmachine]

Pinging @elastic/ml-ui (:ml)