LP#2048907: remove .angular from release tarballs

LP#2048907: remove .angular from release tarballs

This patch removes the eg2 .angular directory, which
contains build artifacts incuding the Angular build
cache, in the course of building release tarballs.

Release-note: Reduce size of release tarball by not shipping the Angular build cache

To test
-------
[1] Apply the patch and use make_release to build a
    tarball.
[2] Verify that the tarball is smaller.
[3] Verify that the Angular staff interface still works
    in an Evergreen instance installed from the tarball .

Signed-off-by: Galen Charlton <gmc@equinoxOLI.org>
Signed-off-by: Jane Sandberg <sandbergja@gmail.com>