Increment TeX counters for the HCT migration notification.

See the corresponding TeX change for more details.

Bug: 369906140
Flag: com.android.graphics.hwui.flags.high_contrast_text_small_text_rect
Test: run statsd_testdrive 644 and verify the output when the
      notification appears
Test: ensure that rotating / restarting the activity does not trigger
      multiple increments to the counter
Change-Id: Iea01962611e3e327cfbde6f3451f7f1ec54b955e