Clean up update sites

The UIMA project dist area [1] appears to have more versions present
than it should.
The policy can be found at [2] under the "Current and older releases" heading.

In particular, there appear to be lots of versions of the individual components
under the Eclipse Update V3 site.

Any versions that are not being developed should please be removed
from the dist area, and please also update any download pages and
release process documentation accordingly.

[1] https://dist.apache.org/repos/dist/release/uima
[2] https://infra.apache.org/release-download-pages.html

• UIMA Java SDK Update Site
• UIMA Ruta Update Site
• UIMA-AS Update Site