Translation Contributors list includes obsolete strings

[SergeyBiryukov]

Looking into ​BuddyPress translations, I've noticed that @ocean90 somehow managed to translate 294 strings into Russian :)

We've discussed it a bit, and apparently it's because the initial import included the strings for bbPress external, which are now obsoleted.

Should Translation Contributors list exclude counts for obsolete strings?

[SergeyBiryukov]

#1663 was marked as a duplicate.

[SergeyBiryukov]

Another example from #1663:

The contributors table on ​https://translate.wordpress.org/locale/ru/default/wp/dev says I have 3 fuzzy strings. I've checked all the subprojects, and there are no fuzzy strings there.

There should be a way to either find and fix them or exclude them from the contributors table.

[ocean90]

In 4511:

Translate: Show contributor stats only for active originals.

Fixes #1642.