Fix the bug where the added field into the toString implementation does

not have a corresponding %s formatting.

Bug: 239134974
Test: atest frameworks/base/core/tests/coretests/src/android/content/integrity
Test: atest services/tests/servicestests/src/com/android/server/integrity
Change-Id: Ib9c3ecadfc5a823cd4fcd44237b25900f86b4e5c