fix: Fixes custom steps connector lines

[pan-kot]

Description

Fixes vertical steps with custom content.

Before:

After:

Rel: AWSUI-62077

How has this been tested?

• Tested in permutation pages

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.51%. Comparing base (57994f0) to head (b71ca2e).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4613      +/-   ##
==========================================
- Coverage   97.51%   97.51%   -0.01%     
==========================================
  Files         948      948              
  Lines       30335    30334       -1     
  Branches    11058    11057       -1     
==========================================
- Hits        29581    29580       -1     
+ Misses        747      707      -40     
- Partials        7       47      +40     

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