Remove notification right after clicking on cancel

After aosp/1188881, DynamicSystemManager.remove() is blocked for
about 30 seconds. To give users feedbacks faster when they click on
the [Cancel] button, This CL removes the progress notification
earlier.

Bug: 145891864
Test: Clicking on the [Cancel] button
Change-Id: I4e43775b2de6eaa50d4a1cc073a5057f22f6d8d5
1 file changed