Remove InputMethodManager#reportActivityView()

This CL logically reverts my previous CL [1], which re-enabled
CursorAnchorInfo API for ActivityView since ActivityView is finally
removed [2].

There should be no user/developer impact in this CL as

   InputMethodManager#reportActivityView()

is called nowhere.

 [1]: Id0411a80456182111bb5b681c6d1230b58e7ec2e
      b4f328a2
 [2]: Ic66f3740819634366edb20a34a7c8177af258c2f
      5456990f

Bug: 115693908
Bug: 179161778
Test: atest CtsInputMethodTestCases
Test: atest CtsWindowManagerDeviceTestCases:ActivityViewTest
Change-Id: Idd60d96a39f827197d189beb5de016446576d9cd