Log a warning if content view exceeds char limit

1. Remove the exception for content view char limit and log a warning
   instead
2. Truncate and ellipsize if it exceeds the char limit

Flag: android.hardware.biometrics.custom_biometric_prompt
Test: atest PromptContentViewScreenshotTest
Bug: 359957211
Change-Id: I76921d118f9510457a8cb953a350259bd42eb17c