Remove log that we will drop event soon

We already have an initial log that event will be dropped in 5 seconds.
No need to keep repeating it.

Bug: 165369992
Test: adb shell monkey 10000, then in a separate terminal: `logcatcolor
| grep -i inputdispatcher` and observe the absence of these logs, but
the presence of the logs 'waiting because ... will wait for'.

Change-Id: I2cce903e95e4f87c5d5efb19d69d94eea82388e5