Remove redundant double "now" in JavaDocs for mock without class

[DerFrZocker]

Will reading the Java Docs for mockito I noticed, that there is a double "now" in the description for mock without class, this PR removes the double now.

Checklist

• Read the contributing guide
• PR should be motivated, i.e. what does it fix, why, and if relevant how
• If possible / relevant include an example in the description, that could help all readers
  including project members to get a better picture of the change
• Avoid other runtime dependencies
• Meaningful commit history ; intention is important please rebase your commit history so that each
  commit is meaningful and help the people that will explore a change in 2 years
• The pull request follows coding style
• Mention Fixes #<issue number> in the description if relevant
• At least one commit should mention Fixes #<issue number> if relevant

[TimvdLippe]

Good spot!