fix(test): clear and close lmdb after each test suite

[pieh]

Description

First problem - our test suites are not really isolated when it comes to lmdb - once lmdb is opened in a process it will remain opened until closed.

Second problem - global is resetted between test suites/files - that means neither we or lmdb internally can use anything "global" like to prevent opening new dbs in new test suites tespite those dbs being in fact already openend.

This PR does few things:

• make use of custom environment to just close all lmdb instances after test suite is done to prevent dangling open handles (it can read global object for the test suite that might have been mutated - in our case references to open lmdb dbs)
• add global tracking for cache-lmdb (we already use it for datastore)

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