Fix incorrect calculation in indexTree.treePosToPath operation

[7hong13]

What this PR does / why we need it?

Any background context you want to provide?

What are the relevant tickets?

• Fix incorrect calculation in indexTree.treePosToPath operation yorkie-js-sdk#751

Fixes #

Checklist

• Added relevant tests or not required
• Didn't break anything

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (0f64efb) 79.61% compared to head (a26048d) 79.63%.

Files	Patch %	Lines
...orkie/src/main/kotlin/dev/yorkie/util/IndexTree.kt	78.57%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #158      +/-   ##
==========================================
+ Coverage   79.61%   79.63%   +0.02%     
==========================================
  Files          63       63              
  Lines        3851     3855       +4     
  Branches      604      606       +2     
==========================================
+ Hits         3066     3070       +4     
  Misses        459      459              
  Partials      326      326              

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