[lldb/test] Fix app_specific_backtrace_crashlog.test (NFC)

This patch fixes app_specific_backtrace_crashlog.test.

It was failing because one of the loaded images was built with
optimization which added a new warning message between the first
`CHECK` and the `CHECK-NEXT`, breaking the expected ordering.

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>