[Improve]: support negative-label property queries with complete index coverage

[contrueCT]

Feature Description (功能描述)

Background

PR #2994 keeps queries that combine a negative label predicate with user-property
filters on the conservative no-index path. This prevents an index plan from
returning only the subset of labels that happen to have a compatible index.

Problem

Consider:

g.V().has(T.label, P.neq("author")).has("city", "Beijing")

The labels that can satisfy this query may include person, fan, and
follower. If only person has a city index, selecting that index returns
matching person vertices while silently omitting matching fan and
follower vertices.
An available partial index must never be used when it cannot produce a complete
candidate set.

Goal

Safely support negative-label predicates combined with property filters while
preserving complete query results.

Requirements

• Determine all schema labels that can satisfy the negative-label predicate and
• expose the queried property.
• Select an index plan only when every eligible label has compatible index
• coverage.
• When coverage is incomplete, either reject with NoIndexException or use an
• explicitly bounded complete-scan plan.
• Never return a partial indexed subset as the query result.
• Preserve the current behavior of pure label predicates, for example:
• g.V().has(T.label, P.neq("author")).
• Cover neq, NOT_IN / equivalent flattened predicates, and multi-label
• cases where only some labels are indexed.
• Add tests that verify no eligible label is skipped and that paging/limit are
• applied only after a complete candidate set is established.

Related

#2992
PR #2994