Remove "Approve" bulk action when viewing spam comments as it isn't shown in...

Remove "Approve" bulk action when viewing spam comments as it isn't shown in the row actions. Props russellwwest. Fixes #20123.


git-svn-id: https://core.svn.wordpress.org/trunk@20533 1a063a9b-81f0-0310-95a4-ce76da25c4cd