fix: move in return stmt preventing copy elision

[CuriousCorrelation]

• What kind of change does this PR introduce?
  Fixes Return unique_ptr directly in GetIterator #2004
  Follows suggestion from the issue desc.

• What is the current behavior?
  Move prevents copy elision
  https://pvs-studio.com/en/docs/warnings/v828/
  https://en.cppreference.com/w/cpp/language/copy_elision

• What is the new behavior?
  Copy Elision is guaranteed when an object is returned directly (>C++17)

[github-actions]

Linux Test Report

       56 files       195 suites   50m 20s ⏱️
  8 958 tests   8 954 ✔️ 4 💤 0 ❌
13 184 runs  13 180 ✔️ 4 💤 0 ❌

Results for commit 259f7dc.

♻️ This comment has been updated with latest results.

[github-actions]

HybridSE Linux Test Report

19 091 tests   19 089 ✔️  5m 27s ⏱️
     235 suites           2 💤
       67 files             0 ❌

Results for commit 259f7dc.

♻️ This comment has been updated with latest results.

[github-actions]

SDK Test Report

  75 files    75 suites   5m 44s ⏱️
163 tests 161 ✔️ 2 💤 0 ❌
204 runs  202 ✔️ 2 💤 0 ❌

Results for commit 259f7dc.

♻️ This comment has been updated with latest results.

[github-actions]

HybridSE Mac Test Report

19 091 tests   19 089 ✔️  6m 35s ⏱️
     235 suites           2 💤
       67 files             0 ❌

Results for commit 259f7dc.

♻️ This comment has been updated with latest results.

[codecov]

Codecov Report

Merging #2012 (259f7dc) into main (855bb52) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##               main    #2012      +/-   ##
============================================
- Coverage     75.61%   75.59%   -0.02%     
  Complexity      347      347              
============================================
  Files           612      612              
  Lines        116943   116924      -19     
  Branches       1022     1022              
============================================
- Hits          88425    88391      -34     
- Misses        28309    28324      +15     
  Partials        209      209              

Impacted Files	Coverage Δ
hybridse/include/codec/list_iterator_codec.h	80.85% <100.00%> (-0.21%)	⬇️
...s/query_response_time/deploy_query_response_time.h	81.25% <0.00%> (-18.75%)	⬇️
hybridse/src/codegen/aggregate_ir_builder.h	95.45% <0.00%> (-4.55%)	⬇️
...atistics/query_response_time/query_response_time.h	78.26% <0.00%> (-4.35%)	⬇️
.../query_response_time/deploy_query_response_time.cc	97.10% <0.00%> (-2.90%)	⬇️
src/sdk/db_sdk.cc	63.90% <0.00%> (-0.45%)	⬇️
src/tablet/tablet_impl.cc	59.30% <0.00%> (-0.15%)	⬇️
hybridse/src/codegen/aggregate_ir_builder.cc	97.05% <0.00%> (-0.15%)	⬇️
hybridse/src/codegen/fn_let_ir_builder.cc	95.34% <0.00%> (-0.08%)	⬇️
hybridse/src/vm/runner.cc	67.73% <0.00%> (-0.04%)	⬇️
... and 9 more

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