[CBRD-23658] counting Error occurred when argument of COUNT function is constant 'NULL'.

[shparkcubrid]

http://jira.cubrid.org/browse/CBRD-23658

This issue is a regression of CBRD-21694
In CBRD-21694, logic to change count_star when argument of count function is constant has been added.

When the argument of the count function is null, I modify it so that it does not change to count_star.
And I eliminates unnecessary duplicate logic in the type check.

[codecov-io]

Codecov Report

Merging #2296 into develop will increase coverage by 2.27%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop    #2296      +/-   ##
===========================================
+ Coverage    46.52%   48.79%   +2.27%     
===========================================
  Files          491      491              
  Lines       384908   384890      -18     
===========================================
+ Hits        179068   187797    +8729     
+ Misses      205840   197093    -8747     

Impacted Files	Coverage Δ
src/parser/type_checking.c	57.53% <100.00%> (+6.30%)	⬆️
src/storage/extendible_hash.c	22.08% <0.00%> (-11.72%)	⬇️
src/query/regu_var.cpp	13.84% <0.00%> (-10.77%)	⬇️
src/base/perf_monitor.h	43.02% <0.00%> (-6.98%)	⬇️
src/thread/thread_daemon.hpp	93.33% <0.00%> (-6.67%)	⬇️
src/query/query_dump.c	50.36% <0.00%> (-4.61%)	⬇️
src/thread/critical_section.c	43.35% <0.00%> (-3.59%)	⬇️
src/base/chartype.c	92.85% <0.00%> (-3.58%)	⬇️
src/query/partition.c	73.46% <0.00%> (-3.41%)	⬇️
src/storage/btree_load.c	72.66% <0.00%> (-2.29%)	⬇️
... and 130 more

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[shparkcubrid]

I accidentally merged incorrectly.
If there are no problems with the review, I will remove the revert PR.