Remove log4j and its references from opencensus am: 8fd12cb94e am: 1109620313 am: 1a0247bd40 am: ef47135fc4

Original change: https://android-review.googlesource.com/c/platform/external/opencensus-java/+/1927168

Change-Id: I04aed30b35d36a3bdef9c01125175f53b7199297