[PATCH]Refactor and unify expression construction functions in makefuncs.c

Hi， Hackers
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While reviewing commit cf6723 (Make transformAExprIn() return a flattened bool expression directly), 
I found several near-duplicate function implementations in makefuncs.c that can be refactored to 
simplify and clean up the codebase.
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This patch performs a set of minor, low-impact clean-up refactors to unify internal expression construction logic:
- make_andclause() / make_orclause() / make_notclause(): Rework these functions to directly call makeBoolExpr(), 
  aligning their implementation style with the existing makeAndExpr() / makeOrExpr() / makeNotExpr() logic in gram.y.
  This eliminates redundant duplicate code for boolean clause construction.
- makeSimpleA_Expr() --> makeA_Expr(): Remove the trivial wrapper function and use the core makeA_Expr() directly to
  simplify expression building logic.
- makeDefElemExtended() --> makeDefElem(): Remove the extended wrapper and adopt standard makeDefElem() uniformly for  
  definition element construction.
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All changes are pure code cleanup with zero functional change.
The patch has minimal code intrusion, only optimizing internal function call chains without altering runtime behavior.
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Test cases are added for every refactored function to guarantee correctness and prevent regression:
  - make_andclause() --> makeBoolExpr(): SELECT * FROM t1 WHERE id = 1 AND id = 3;
  - make_orclause() -->  makeBoolExpr(): SELECT * FROM t1 WHERE id = 1 OR id = 3;
  - make_notclause() --> makeBoolExpr(): SELECT * FROM t1 WHERE id NOT IN (1);
&nbsp; - makeSimpleA_Expr() --&gt; makeA_Expr(): SELECT oid::integer+1 FROM pg_class WHERE oid::integer+1 < 100;
&nbsp; - makeDefElemExtended() --&gt; makeDefElem():&nbsp; &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp; &nbsp; CREATE SERVER myserver FOREIGN DATA WRAPPER postgres_fdw OPTIONS (host 'foo', dbname 'foodb', port '5432');
&nbsp; &nbsp; &nbsp; ALTER SERVER myserver OPTIONS (DROP port);
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All newly added tests pass successfully, verifying that the refactoring is safe, consistent and introduces no behavioral changes.

Thanks,
--
ZizhuanLiu&nbsp;(X-MAN)&nbsp;
44973863@qq.com