Remove page heading in feature flags empty state

Problem to solve

Currenlty, feature flags empty state is using a heading (Feature flags) which breaks top area navigation into 2 separate lines. Navigation controls should be in the same line with the tab filters (All, Enabled, Disabled). This was probably done because feature flags MVC (see !7433 (merged)) didn't include tab filters (see !8821 (merged)).

Proposal

Current	Proposed