Increase volume search timeout, fix dialog flow.

Slower devices can take longer to process kernel events, so try up
to 25 times (~6 seconds) to find the volume after the partitioning
is finished.

Fix bug where we'd finish() while trying to show the format
confirmation dialog, meaning users couldn't format corrupted
non-primary volumes.

Bug: 74129968, 77849654, 74132243
Test: atest com.android.settings.ui.StorageWizardTest
Change-Id: I91144051cb6de0cd944d93b03dc5127676e24be8