See also #28491#31240
When colleciton number is large, querycoord saves collection target one
by one, which is slow and may block querycoord exits.
In local run, 500 collections scenario may lead to about 40 seconds
saving collection targets.
This PR changes the `SaveCollectionTarget` interface into batch one and
organizes the collection in 16 per bundle batches to accelerate this
procedure.
Signed-off-by: Congqi Xia <congqi.xia@zilliz.com>
8e5865f630