Fix the RemoteInputViewTest mock user context

SystemUI needs to handle multiple user environment but the systemuitest
doesn't simulate appropriately. To use spy mocks the
Context.createContextAsUser. When the test is running, the real
environment doesn't have the such user. That's why the
IllegalStateException comes out.

Fixes: 169302704
Test: TID="SystemUITests"; \
      PACKAGE_NAME="com.android.systemui.statusbar.policy"; \
      TEST_CLASS="RemoteInputViewTest"; \
      atest "${TID}:${PACKAGE_NAME}.${TEST_CLASS}"
Change-Id: I3041226496c641dad11b415173675e09186d318a