Revert "Make PrecomputedText Spannable for supporting selection"

Crash on Sheets APp
This reverts commit 80ed5a35a90b62b8070d861b9755e230bd679951.

Bug: 75652829
Change-Id: I40ddd1b9754e74fbd90d7a029cce9c6a7ede0777
Test: Manual
6 files changed