Fix crash in some cases of recursive procedure calls

[tanscorpio7]

Description

Fix crash when we recursively execute a function or procedure and the call was made from the same line of the procedure. For ex:

CREATE PROCEDURE babel_4782_p(@in INT) AS
IF (@in = 1)
BEGIN
        SELECT 1;
END
ELSE
BEGIN
        SET @in = @in - 1
        /*
         * Below line will call the procedure babel_4782_p recursively. The plan for this call stmt is
         * cached in PLtsql_stmt_exec node. Now when we recursively execute the same line again, 
         * we will use the cached PLtsql_stmt_exec node which will also have the plan cached in it.
         */
        EXEC babel_4782_p @in
END
GO

In such recursive calls the plan in the outer call gets used by the inner call & at the end of execution we would free the plan even when the outer call is still active and using it. The cached plan is only available at statement level, hence the statement making the call should be same. As a fix we only free the plan in an exec stmt if we generated it in the first place. This is just a quick fix for now but a proper solution would be to adopt postgres method of caching the plan for exec calls.

Issues Resolved

[BABEL-4782]

Check List

• [x] Commits are signed per the DCO using --signoff

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[coveralls]

Pull Request Test Coverage Report for Build 9446296015

Details

• 4 of 4 (100.0%) changed or added relevant lines in 1 file are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.004%) to 73.058%

---

Files with Coverage Reduction	New Missed Lines	%
contrib/babelfishpg_tds/src/backend/tds/tdscomm.c	3	73.33%
<!--	Total:	3		-->

Totals
Change from base Build 9416708039:	-0.004%
Covered Lines:	42283
Relevant Lines:	57876

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 9452589260

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
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• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 6 of 6 (100.0%) changed or added relevant lines in 1 file are covered.
• 52 unchanged lines in 1 file lost coverage.
• Overall coverage remained the same at 73.062%

---

Files with Coverage Reduction	New Missed Lines	%
contrib/babelfishpg_common/src/datetime.c	52	92.57%
<!--	Total:	52		-->

Totals
Change from base Build 9416708039:	0.0%
Covered Lines:	42284
Relevant Lines:	57874

---

💛 - Coveralls