Description:
===========
This WL focuses on improving check-testcases logic in MTR. MTR check-testcases
perform checks just before and after the test execution to ensure there are no
changes in the internal state of the Database.

Multiple scenarios were seen where the test does not perform cleanup after itself
eg - (check for persisted variables, check for leftover files in var/tmp dir) etc

Solution:
========
Below are the new checks introduced as part of WL#10928:

1. check for persisted variables.
2. check for any left behind tablespaces.
3. check for any active/open connection.
4. check for any left-over files.
5. check for installed plugins/components.
6. check for new plugin/component variables.
7. check for new UDFs.

Reviewed by:
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Pavan Naik <pavan.naik@oracle.com>
Srikanth B.R <srikanth.b.r@oracle.com>
Narendra Chauhan <narendra.chauhan@oracle.com>