Fix CTS TextViewTest

Id65a7e36487375f0e3a2c2da44ad8d7c5ea49734 changes the typeface
associated with the TextView. It used be null if no attribute was set,
but after above change, it is now Typeface.DEFAULT.

The typeface is null means Typeface.DEFAULT but there is an expectations
in CTS that getTypeface must return null if no attribute was set.

To keep this behavior, call setTypeface with null if no font weight value
was set.

Bug: 74080879
Test: atest CtsWidgetTestCases:EditTextTest
    CtsWidgetTestCases:TextViewFadingEdgeTest
    FrameworksCoreTests:TextViewFallbackLineSpacingTest
    FrameworksCoreTests:TextViewTest FrameworksCoreTests:TypefaceTest
    CtsGraphicsTestCases:TypefaceTest CtsWidgetTestCases:TextViewTest
    CtsTextTestCases FrameworksCoreTests:android.text

Change-Id: Ic91827bbeed8a3a4b148dd8d305c78e384407ab0