smart search: schema-qualify vector type

test plan:
 - predeploys run

flag=smart_search
refs ADV-22

Change-Id: I3c1c303e804307b154cc5ca8dfb4280ea161c601
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/327269
Migration-Review: Isaac Moore <isaac.moore@instructure.com>
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Jonathan Featherstone <jfeatherstone@instructure.com>
QA-Review: Jeremy Stanley <jeremy@instructure.com>
Product-Review: Jeremy Stanley <jeremy@instructure.com>

db/migrate/20230901164455_add_wiki_page_embeddings.rb

@@ -27,7 +27,10 @@ class AddWikiPageEmbeddings < ActiveRecord::Migration[7.0]
     enable_extension("vector")
     create_table :wiki_page_embeddings do |t|
       t.references :wiki_page, null: false, foreign_key: true
-      t.column :embedding, :vector, limit: 1536, null: false
+      t.column :embedding,
+               "#{connection.extension("vector")&.schema || "public"}.vector",
+               limit: 1536,
+               null: false
       t.timestamps null: false
       t.references :root_account, foreign_key: { to_table: :accounts }, index: false, null: false
     end