refactor(frontend): rename __rw_vnode to rw_vnode

[stdrc]

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What's changed and what's your intention?

Little renaming.

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
• All checks passed in ./risedev check (or alias, ./risedev c)

Refer to a related PR or issue link (optional)

#4327 (comment)

[codecov]

Codecov Report

Merging #4342 (bbdf0b5) into main (c87f9b5) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #4342   +/-   ##
=======================================
  Coverage   74.41%   74.41%           
=======================================
  Files         843      843           
  Lines      122713   122713           
=======================================
  Hits        91316    91316           
  Misses      31397    31397           

Flag	Coverage Δ
rust	74.41% <100.00%> (ø)

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Impacted Files	Coverage Δ
src/frontend/src/binder/expr/function.rs	80.15% <100.00%> (ø)
src/meta/src/manager/id.rs	95.65% <0.00%> (ø)

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