Stop copying PrecomputedText buffer

PrecomputedText already has a copy of the text. No need to copy the
buffer.

android.text.StaticLayoutPerfTest:
  draw
    PrecomputedText NoStyle: 610 -> 616: (  +6, +1.0%)
    PrecomputedText Style  : 811 -> 831: ( +20, +2.5%)
    RandomText NoStyle     : 547 -> 544: (  -3, -0.5%)
    RandomText Style       : 730 -> 744: ( +14, +1.9%)

Bug: 72461923
Test: atest CtsWidgetTestCases:EditTextTest
    CtsWidgetTestCases:TextViewFadingEdgeTest
    FrameworksCoreTests:TextViewFallbackLineSpacingTest
    FrameworksCoreTests:TextViewTest FrameworksCoreTests:TypefaceTest
    CtsGraphicsTestCases:TypefaceTest CtsWidgetTestCases:TextViewTest
    CtsTextTestCases FrameworksCoreTests:android.text
    CtsWidgetTestCases:TextViewPrecomputedTextTest
Change-Id: I4b9d1c003f127a796d7d4f0d4aecfa7d016b89f6