Improve Settings launch performance

From traces analysis, we found getFreeBytes
was taking a long time to return.

getFreeBytes was used when storage controller
tried to get storage information.

In order to prevent this case, we put the action
which takes too much time in background thread.

Test: I can't reproduce it locally. From code view,
this is a reasonable root cause.
Fixes: 136268875

Change-Id: I78e42cde88553c003f198cffb5747b352055f59a
(cherry picked from commit 0c37f019)