Delete a bunch of unnecesary EPPlus projects. Change-Id: I3d7595083497be0af5e97dba1029e8b2b8eb5f22 Reviewed-on: https://gnocchi-internal-review.git.corp.google.com/c/third_party/epplus/+/207481 Reviewed-by: Hughes Hilton <hugheshilton@google.com> Autosubmit: Brian Cairns <bcairns@google.com>