Hide eject icon of removable media when it's emulated volume

Hide eject icon of removable media on the root list of Files app when
primary shared storage is in adopted media due to the following reasons.

- Primary shared storage should not be easily ejected because that
causes the situation that there's no primary shared storage

- To align with the Storage settings (Settings > Storage), eject icon
is disabled in this menu when the removable media is adopted

- Eject action from Files app can only unmount primary shared storage

Bug: 117252468
Test: manual
Change-Id: Idd76229fb10db621a817afd60295787c761345b1