Stop inheriting TextPaint and use self crafted font for testing.

getTextRunAdvances is a private API.
This is groundwork for removing addMeasuredRun from StaticLayout.
There is a special hack in MeasuredText to work with overloaded
getTextRunAdvances but getTextRunAdvances is private API. Looks like
this test is the only user of that hack.

Bug: 67009717
Bug: 65024629
Test: bit FrameworksCoreTests:android.text.StaticLayoutLineBreakingTest
Change-Id: I2c0f0365824caef6959b213ddae5a03f8cf62c7c