Improve volume panel open-settings transitions.

Removing animation style removes fading from panel open-close which
looks better.
Intent flag slightly improves transitiong to the settings when it's
already opened.

Flag: aconfig new_volume_panel TEAMFOOD
Test: manual on the phone. Open settings using a button in the bottom
bar of the volume panel.
Bug: 330105146

Change-Id: Ic37f8314d1375ff94414594ccee18ed1512aa6e3