After schema reload, `target_parser::is_local()` did not recognize the
vector-index local target format `{"pk": [...], "tc": "..."}`, causing
local vector indexes to be treated as global. This broke duplicate
detection when both a global and a local vector index existed on the same
column. Fix by introducing `vector_index::is_local()` and dispatching
to it from `create_index_from_index_row()` based on the index class.
Also adds tests for local/global vector index coexistence.
Fixes: SCYLLADB-2315
backport reasoning: we added local vector index support in 2026.1
- (cherry picked from commit cf372ba87b)
- (cherry picked from commit 119ef942f8)
Parent PR: #29492Closesscylladb/scylladb#30123
* github.com:scylladb/scylladb:
test/cqlpy: add tests for global and local vector index coexistence
index: fix local vector index locality detection after schema reload
e94d305856