Drop 'comma' value for wgArticleCountMethod

Drop 'comma' value for wgArticleCountMethod

We have three methods for page counting currently supported for wikitext
non-redirect pages; 'any' counts any page that exists, 'link' counts any
page that has any outbound links, and 'comma' which searches for any ','
in the text having loaded it. This last option is much slower than these
other two, and is only used on a very small number of installations. Now
by dropping support for this method we can simplify this code and so run
it more often. Note that non-wikitext pages already did not support this
count method.

Installations with this setting set to 'comma', or any other string will
now work as if it was configured with 'any'.

Bug: T188472
Change-Id: I965927edcd2485ec4b49b2d80fdf216dbf19520b