SessionHL::Pull built a fine-grained auth checker whenever an authenticated
user was present, but -- unlike the three call sites in interpreter.cpp -- did
not first check that the enterprise license is valid.
AuthChecker::GetFineGrainedAuthChecker returns a null unique_ptr the moment the
license is invalid, so on an enterprise binary running without a valid license
the following `auth_checker->NeedsFineGrainedAuthChecker()` dereferenced null
and crashed the server (the DMG_ASSERT guarding it is compiled out in release
builds).

Restore the invariant the DMG_ASSERT documents by gating the block on
license::global_license_checker.IsEnterpriseValidFast(), matching the other
call sites. When the license is invalid, fine-grained filtering is simply not
applied (community-legal) and the query returns cleanly.

The crash reproduces whenever an enterprise binary runs unlicensed and any
authenticated user (QueryUserOrRole is truthy iff a username is set -- a role is
not required) runs a data query. QA hit it by creating a role under a valid
license and then dropping the license; that role and license drop are
incidental to the crash.

Regression test: fine_grained_access/unlicensed_user_query_crash_tests.py.
It cannot use a runner-managed `cluster:` instance because CI supplies the
license via env (MEMGRAPH_ENTERPRISE_LICENSE / MEMGRAPH_ORGANIZATION_NAME) and
the license resolver keeps the valid ENV candidate even after `SET DATABASE
SETTING 'enterprise.license' TO ''`, so the license can't be dropped at runtime.
Instead the test self-manages its instance via interactive_mg_runner and pops
the license env vars before start (Popen inherits the mutated os.environ), so
Memgraph boots unlicensed. It then creates a user, runs a data query as that
user, and asserts the query returns cleanly and the server stays alive.

Claude-Session: https://claude.ai/code/session_01S7bHLYsqWYDtsuR9oK3K37