Enable winscope tracing in multi user IME CTS test

This enables winscope tracing for multi user IME CTS tests, as well as
collecting a screenshot on  failure. It is configured to capture a
single trace for the entire test class run, and collect it at the end if
any failure occurred.

Flag: EXEMPT testfix
Bug: 403237498
Test: atest CtsInputMethodInstallTestCases
Change-Id: Id58df3203158cb235c9dc1c5acce365f062b6f01