Postpones the fill UI if the save UI is showing

A new fill request will cause the save UI to be hidden immediately. So
postpone the fill UI when the save UI is showing. And reshow the fill UI
after the save UI disappear.

Fixes: 139876545
Test: manual
Test: atest CtsAutoFillServiceTestCases
Change-Id: Ibb1ab903ae1fb70ee5e5f386c522f65f6c2cfa8e