Fix Postgresql JDBC driver leaking memory
Fix Postgresql JDBC driver leaking memory

Older versions of Postgresql JDBC driver rely on finalize() methods in
order to avoid leaking unclosed database objects. Given finalize
methods are unpredictable (no guarantee about prompt execution, if at
all), in some high load environments this could lead to a memory leak
with millions of JDBC objects pending finalization.

Newer versions of the Postgresql JDBC driver removed the use of finalize
methods to avoid this kind of issues.

Bug: Issue 4848
Change-Id: Ia143f1df1d8e41686362fd76b9bc82e0046f9894

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