fix scale settings seekbar to match actual scale

Test: atest SystemUITests
Test: manual test - video attached to the bug
Bug: 271498519

Few TODOs still:
1) Working with small scale in progress bar is very difficult now that max value is higher.
Follow up changelist will implement interpolation to make smaller scale work better with gradient progressbar.

2) In ZoomSeekBarChangeListener, onProgressChanged, any values smaller than persisted min value (1.3f) will
not update secure settings. I need to follow up with Roy on the logic to ensure this is expected behaviour
when we update settings.

3) ContentObserver is sometimes not fired. Perhaps similar to logic above, there might be a logic that
bypasses updating SecureSettings from service. Follow up with Roy to fix this.

Change-Id: Ia245241844e82b99838ebc817a12edc46ee0337a