Set 2-pane placeholder for all alias of SettingsHomepageActivity

SettingsHomepageActivity may be launched by different alias,
this change sets placeholder for all these alias to ensure
placeholder is present.

Bug: 199363383
Test: manual
      1. Click Settings icon button in quick setting panel.
      2. Launch Settings app deep link, then move it to background,
         and the launch Settings app.
Change-Id: I9ba6dbc5cfa2bac51bf53bb21f8983193ba053b6