Use correct plural form for zero

[berland]

If there are no forward_model_steps, we should write '0 steps', not '0 step'

Issue
Resolves remainder of #7911

Approach
Fix.

• PR title captures the intent of the changes, and is fitting for release notes.
• Added appropriate release note label
• Commit history is consistent and clean, in line with the contribution guidelines.
• Make sure tests pass locally (after every commit!)

When applicable

• When there are user facing changes: Updated documentation
• New behavior or changes to existing untested code: Ensured that unit tests are added (See Ground Rules).
• Large PR: Prepare changes in small commits for more convenient review
• Bug fix: Add regression test for the bug
• Bug fix: Create Backport PR to latest release

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.37%. Comparing base (4681ad7) to head (cb5b550).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7925      +/-   ##
==========================================
- Coverage   85.37%   85.37%   -0.01%     
==========================================
  Files         381      381              
  Lines       23706    23709       +3     
  Branches      884      892       +8     
==========================================
+ Hits        20240    20242       +2     
- Misses       3353     3360       +7     
+ Partials      113      107       -6     

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[jonathan-eq]

LGTM!