Reset the clang-format standard to c++17

[yixinglu]

as title.

[codecov-commenter]

Codecov Report

Merging #3076 (4c730ab) into master (e1de5af) will increase coverage by 0.03%.
The diff coverage is 77.14%.

@@            Coverage Diff             @@
##           master    #3076      +/-   ##
==========================================
+ Coverage   84.24%   84.27%   +0.03%     
==========================================
  Files        1287     1287              
  Lines      115639   115644       +5     
==========================================
+ Hits        97415    97457      +42     
+ Misses      18224    18187      -37     

Impacted Files	Coverage Δ
src/common/base/EitherOr.h	95.67% <ø> (ø)
src/common/base/ErrorOr.h	100.00% <ø> (ø)
src/common/thrift/ThriftClientManager.h	100.00% <ø> (ø)
src/graph/service/GraphService.cpp	74.60% <0.00%> (-1.21%)	⬇️
src/common/datatypes/DataSetOps-inl.h	49.39% <66.66%> (ø)
src/common/datatypes/ListOps-inl.h	66.10% <66.66%> (ø)
src/common/datatypes/SetOps-inl.h	49.12% <75.00%> (ø)
src/common/datatypes/EdgeOps-inl.h	47.46% <80.00%> (ø)
src/common/datatypes/PathOps-inl.h	52.79% <80.00%> (ø)
src/common/datatypes/VertexOps-inl.h	51.06% <80.00%> (ø)
... and 27 more

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