Add testcase for the ref cursor fix

[aashikam]

Purpose

Related: https://github.com/wso2-enterprise/internal-support-ballerina/issues/623

Examples

Checklist

• Linked to an issue
• Updated the specification
• Updated the changelog
• Added tests
• Checked native-image compatibility

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.69%. Comparing base (409d060) to head (5b9a116).

Additional details and impacted files

@@            Coverage Diff            @@
##               main      #20   +/-   ##
=========================================
  Coverage     82.69%   82.69%           
  Complexity       11       11           
=========================================
  Files             6        6           
  Lines           104      104           
  Branches         22       22           
=========================================
  Hits             86       86           
  Misses           10       10           
  Partials          8        8           

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[aashikam]

I have tested this with my redshift clusters and the issue is fixed. Mentioning this here since the test server is a postgres server and somehow gets an error with the PROCEDUREsyntax when creating the stored procedure in the before suite setup, therefore I have used FUNCTION instead for tests. PROCEDURE works in actual redshift cluster.