Upgrade to pantsbuild.pants 0.0.24.

There was 1 api break in BUILD files, repo no longer takes a
`push_db` file, but a `push_db_basedir`.

The rest is cleanups of deprecated aliases:
+ kill `pants()` wrappers
+ s/dependencies/target/
+ use `./pants goal test` in ci.sh for python tests

The pants-plugins/ needed no changes.

https://rbcommons.com/s/twitter/r/1071/