Make rejected photos aren't computed in user's stats

[nilovelez]

Currently, both submissions errors like theese:
https://meta.trac.wordpress.org/ticket/7565

...and photos moderators reject as "Error: submission error" are counted while computing user stats. This seems unfair for users and might give moderators a wrong impression while evaluating a user.

I think both of this cases should be excluded from stats, and maybe others

[coffee2code]

Just to be clear, photos rejected as being a "submission-error" are ​already excluded from the calculation of the rejection rate warning (the number of rejections relative to their total number of submissions).

But the number of rejected submissions shown in admin photo listings in the author column does indeed currently include submission errors, so that should change.

The only other shown count that includes submission errors is the link above admin photo listing tables (e.g "Rejections (3,234)"), but I don't feel that needs to ignore submission errors.

Other than 'submission-error', I'm not sure that any other rejection reason warrants being omitted from the rejection count as it's the only one that is generally out of the control of contributors.

[coffee2code]

In 13784:

Photo Directory, User: Exclude submission errors by default when calculating the count of a user's rejections.

Props nilovelez, coffee2code.
Fixes #7588.