fix(hstore): invalidate graph registration after clear

[ulofiai]

Fixes the HStore clear/recreate lifecycle defect described in #3090.

This focused change invalidates the local infoInitializedGraph marker after a successful store-side graph deletion. The marker is cleared in a finally block, so a later open() can re-register the same graph even when the PD deletion call reports an error.

A regression test repeats the initialization-state add/clear transition 50 times to guard against stale JVM lifecycle state.

Validation:

• git diff --check
• Java 11 syntax parsing for both modified sources
• patch apply and reverse-apply checks against the supplied base snapshot

Maven tests were not run because Maven is unavailable in the execution image.

[imbajin]

Blocking: no. Summary: The production change clears the stale registration marker after graph deletion, but the added regression test only exercises the private helper and does not validate the public clear/recreate lifecycle. Evidence: Static review of HstoreSessionsImpl.clear() and HstoreSessionsImplTest.testClearInitializedGraphStateRepeatedly(); no CI checks reported for this exact head.

[imbajin]

⚠️ This test invokes private clearInitializedGraph() via reflection instead of exercising HstoreSessionsImpl.clear(). It would still pass if the finally call at HstoreSessionsImpl.java:188 were removed or misplaced, and it does not verify the reported clear/recreate lifecycle. Please cover the public clear path (ideally the repeated clear/recreate sequence) and assert that a subsequent open re-registers the graph, or use controllable fakes to verify that behavior.