Remove redundant setting of DistFiles by apexBundle

A previous change handles dist properties automatically for all module
types and as a result has made the apexBundle setting of DistFiles
redundant so this change removes that.

Test: m nothing
      m dist sdk - before and after this change, compare result to
      make sure that there are no significant differences.
      Test the effect on the apex by following instructions in
      http://b/172951145
Bug: 174226317
Change-Id: If6f741b5b73b3335f4c478a6528f5f311cd633e4