fix(analytics): 14294 - prevent init of analytics with empty features

[propakov]

https://kontur.fibery.io/Tasks/Task/After-several-updates-the-initial-state-of-the-analytics-panel-becomes-advanced-analytics-14294

Context:
Reason of a bug being created - sometimes Analytics initial state is full though it's short set.
After investigation with @Akiyamka we found that the reason is featureFlags being {} at the moment of defining initialState prop:
initialState={featureFlags[FeatureFlag.ANALYTICS_PANEL] ? 'short' : null}
When initialState prop is null, in useShortPanelState it's 'full'.
const initialState = props?.initialState ?? 'full';
So main line here in fix is

    {Object.keys(featureFlags).length > 0 && (
        <Layout

just to render layout after we have features filled.

• Line in src/core/app/features.ts is just redundant, appeared after merge, so remove it.
• fixes in src/core/shared_state/featureFlags.ts don't make a bug, but still incorrect as value out of atom can be mutated, that can lead to bugs