cut 2.13 build waaaaaaaay down to size to be green for M3

[SethTisue]

bye bye scalaz, shapeless, specs2, and tons of other stuff

[SethTisue]

the utest errors are e.g.:

[utest] [error] /home/jenkins/workspace/scala-2.13.x-integrate-community-build/target-0.9.9/project-builds/utest-c283a7598461f9d86d161dabc2278fe9073dc136/utest/shared/src/main/scala/utest/runner/Framework.scala:61: type mismatch;
[utest] [error]  found   : Unit
[utest] [error]  required: () => Unit
[utest] [error]       setup,
[utest] [error]       ^

the eta expansions need to be made explicit.

[SethTisue]

I'm removing collection-strawman for now, but there's already a ticket on that (scala/collection-strawman#308) that I'll revisit soon

[SethTisue]

I opened a scalaz ticket at scalaz/scalaz#1629 and asked @milessabin about Shapeless on Slack.

[SethTisue]

green in local test