Fix validator-outstanding-rewards command

[alexanderbez]

closes: #4493

---

• Targeted PR against correct branch (see CONTRIBUTING.md)

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.

• Wrote tests

• Updated relevant documentation (docs/)

• Added a relevant changelog entry: clog add [section] [stanza] [message]

• rereviewed Files changed in the github PR explorer

---

For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #4494 into master will decrease coverage by 0.06%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #4494      +/-   ##
==========================================
- Coverage   53.22%   53.16%   -0.07%     
==========================================
  Files         259      259              
  Lines       16173    16192      +19     
==========================================
  Hits         8608     8608              
- Misses       6919     6938      +19     
  Partials      646      646