improve umbraco ignores
Remove redundant Umbraco exceptions to VS rules

From the discussion on #1013:

Since the rule in VS is packages/*, the fact that it contains a slash means
that it is anchored to the top level. That is, is will only apply to
a directory called packages at the top level, and not to any at deeper
directories like App_Data. So these rules at the bottom of your changes
actually aren't necessary after all. I just confirmed this with a quick test.
Shorten note in comment at the top
Merge branch 'fix-1013'

I made some changes to the original pull request to remove complexity which
I believe was not needed.