Add testcode for Duplicate deregister in GC

[highcloud100]

What this PR does / why we need it:

There was Duplicate deregister in Nested Object GC error in js sdk.
It was solved by js yorkie-js-sdk/PR #761.

There is no problem with existing code, but add test code that coverage this problem for later in case.

Which issue(s) this PR fixes:

Fixes #

Checklist:

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (8987b45) 49.27% compared to head (fbc7c6d) 49.30%.
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #746      +/-   ##
==========================================
+ Coverage   49.27%   49.30%   +0.03%     
==========================================
  Files          69       69              
  Lines       10087    10094       +7     
==========================================
+ Hits         4970     4977       +7     
  Misses       4601     4601              
  Partials      516      516              

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[highcloud100]

Solved in #756