Fixing Storage Volume(s) Retrieval.

With ag/19901205 shared_profile's volumes were also listed in
StorageManager#updateExternalStorageFileQuotaType.

However, the above API can be called from MediaProvider process,
without MANAGE_EXTERNAL_STORAGE permissions, resulting in
SecurityException("Only File Manager Apps permitted") to be thrown
from StorageManagerService#getVolumeList

This fix allows the exception to be bypassed in case the caller is
Media Store process.

Bug: 235321217
Test: atest android.appsecurity.cts.StorageHostTest
Change-Id: I6835cc4d29f3e9c85731979aaf9ab12a30f6419b