Simplify IMMS#dump() with ArrayUtils.contains()

This is a follow up CL to our previous CL [1], which enabled IME
tracing result to be automatically included into the bugreport.

Checking whether args contain "--proto" or not is something we can
achieve with ArrayUtils.contains() as a one-liner.  Let's do so in
favor of simplicity.

This is a mechanical refactoring hence there should be no behavior
change.

This is a preparation to fix another unintentional behavior change
(Bug 177462676), which was also accidentally introduced in the same
CL.

 [1]: Ie87eb8423e2bb70f28c330983d45b95e2e07062d
      ac24994a

Bug: 154348613
Bug: 167948910
Bug: 177462676
Test: Manually done as follows.
  1. adb shell ime tracing start
  2. adb logcat -s imeTracing:*
       Make sure IME tracing started.
  3. adb shell am start -a android.intent.action.DIAL
  4. adb bugreport bugreport.zip
  5. adb logcat -s imeTracing:*
       Make sure IME tracing is stopped then restarted.
  6. unzip -v bugreport.zip | grep ime_trace_clients.pb
       Make sure "ime_trace_clients.pb" is included.
Change-Id: I057fba86b4ab7d2de1725e73d5a39bb88ee35414