[OSS-ONLY] Update JDBC Framework to run under a single connection

[KushaalShroff]

Description

With this commit we enforce JDBC framework to use and keep re-using only 1 connection through it's entirety. We enable this only for non-upgrade tests for now.
To do so we execute the sp_reset_connection after each test file, using the same connection object. In case of crossdialect files (.mix) we still keep reusing the the same connection unless the user has specified their own --tsql/--psql connections.
While enabling this we encountered a lot of bugs which we fixed and add explicit tests under Test-sp_reset_connection.mix but there are other issues that using one connections bring with it like the drawback of not able to unload pg_hint_plan from the current session and other bugs. To avoid them from failing we update these test files as .mix files with their own "--tsql" connection which gets disconnected at the end of the file.

Issues Resolved

BABEL-5255

Check List

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[coveralls]

Pull Request Test Coverage Report for Build 12505594390

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 5 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.001%) to 74.854%

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Files with Coverage Reduction	New Missed Lines	%
contrib/babelfishpg_tsql/src/pl_funcs.c	2	18.95%
contrib/babelfishpg_tsql/src/pl_funcs-2.c	3	45.82%

Totals
Change from base Build 12502179127:	-0.001%
Covered Lines:	46568
Relevant Lines:	62212

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💛 - Coveralls