Clean up unused LogEvent constructors

After switching to the new socket schema, we can remove certain LogEvent
constructors. AttributionNodeInternal was only used in tests and can be
removed as well.

Bug: 14959031
Test: bit statsd_test:*
Change-Id: Ib5cb6acc50cc4d37a46a076d41face452a0a87d8
6 files changed
tree: 0720222309497ba5bd22a0c705a43e5e087f82da
  1. bin/