Don't skip adding stub home task if applyLoadPlan hasn't run

- In FallbackRecentsTest.goToOverviewFromHome, home task gesture starts before applyLoadPlan, causing shouldAddStubTaskView to return false because getTaskViewCount is 0. This falsely avoid home task to be added to RecentsView, causing the animation to be drastically different from what user sees outside the test
- Added a check on whether applyLoadPlan is ever called to solve the problem

Fix: 205580523
Test: FallbackRecentsTest.goToOverviewFromHome
Change-Id: I2e435e56008e916e8f7e1037d3fa3c8177437d13