Do not show fingerprint icon/circle underneath moving target

During enrollment, we have the two elements:
1) Circle and icon on the actual sensor location
2) Moving target, shown after the user enrolled the central location

To avoid confusion during the second part of enrollment when the
moving target is shown, we should hide the central circle/icon during
moving enrollment.

Bug: 187460696
Test: manual
Change-Id: I2339e80654e0000a56d87901d14a88f8a6a35af1