refactor(yaml): cleanup `stringifyBlockSequence()`

[timreichen]

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 88.88889% with 1 line in your changes missing coverage. Please review.

Project coverage is 96.24%. Comparing base (b91817f) to head (76f6c75). Report is 4 commits behind head on main.

Files	Patch %	Lines
yaml/_dumper_state.ts	88.88%	0 Missing and 1 partial :warning:

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5742   +/-   ##
=======================================
  Coverage   96.23%   96.24%           
=======================================
  Files         479      479           
  Lines       38719    38709   -10     
  Branches     5614     5615    +1     
=======================================
- Hits        37262    37256    -6     
+ Misses       1416     1411    -5     
- Partials       41       42    +1     

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.