Recently new utility methods were added to JdbcTestUtils, and a
JdbcTemplate was introduced in abstract transactional base classes in
the TestContext framework. This presents an easy opportunity to make
these new utility methods available as convenience methods in the base
test classes.

This commit introduces new countRowsInTableWhere() and dropTables()
convenience methods in the abstract transactional base classes in the
TestContext framework. These new methods internally delegate to methods
of the same names in JdbcTestUtils.

Issue: SPR-9665