Add a framework to assert relevant metric values between runs of each test

We should ensure that certain metrics are the expected value in between each test run. For example, each test should ensure resources (such as connections/statements) are closed after their use and can assert that the total Phoenix connection count is zero. 

This Jira broadly aims at 2 things:

1. Modifying existing tests so that we do not leak resources in the test itself
2. Adding a common framework/interface, etc. which all "relevant" tests can inherit behavior to assert specific values for metrics and resource usage like query failure counts, open phoenix connection counts, etc. We can implement something similar as is aimed in PHOENIX-5296

The idea is to use this Jira to brainstorm various ideas. This will also help uncover resource leaks/incorrect metric updates throughout the code base.