fix inconsistent variable in yield and from clause

[czpmango]

What type of PR is this?

• bug
• feature
• enhancement

What does this PR do?

Fix inconsistent variable in yield and from clause.

Which issue(s)/PR(s) this PR relates to?

#3210

Checklist：

• Documentation affected （Please add the label if documentation needs to be modified.)
• Incompatible （If it is incompatible, please describe it and add corresponding label.）
• Need to cherry-pick （If need to cherry-pick to some branches, please label the destination version(s).)
• Performance impacted: Consumes more CPU/Memory

Release notes：

                   `

[codecov-commenter]

Codecov Report

Merging #3430 (88af04f) into master (6ccf173) will increase coverage by 0.02%.
The diff coverage is 72.72%.

@@            Coverage Diff             @@
##           master    #3430      +/-   ##
==========================================
+ Coverage   85.25%   85.27%   +0.02%     
==========================================
  Files        1278     1278              
  Lines      119277   119285       +8     
==========================================
+ Hits       101688   101720      +32     
+ Misses      17589    17565      -24     

Impacted Files	Coverage Δ
src/graph/validator/GoValidator.cpp	96.25% <72.72%> (-0.94%)	⬇️
src/meta/processors/BaseProcessor.h	75.67% <0.00%> (-16.22%)	⬇️
src/common/thrift/ThriftClientManager-inl.h	82.97% <0.00%> (-6.39%)	⬇️
src/parser/GraphScanner.h	91.46% <0.00%> (-2.29%)	⬇️
src/graph/util/SchemaUtil.cpp	92.82% <0.00%> (-0.40%)	⬇️
src/common/datatypes/ValueOps-inl.h	61.29% <0.00%> (-0.21%)	⬇️
src/common/datatypes/GeographyOps-inl.h	51.12% <0.00%> (-0.15%)	⬇️
src/common/datatypes/Value.cpp	75.21% <0.00%> (+0.10%)	⬆️
src/kvstore/NebulaStore.cpp	69.69% <0.00%> (+0.13%)	⬆️
src/clients/meta/MetaClient.cpp	76.36% <0.00%> (+0.16%)	⬆️
... and 12 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6ccf173...88af04f. Read the comment docs.