store/post: fix searching for phrases in postgres (#17042)

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

store/sqlstore/post_store.go

@@ -1490,6 +1490,8 @@ func (s *SqlPostStore) search(teamId string, userId string, params *model.Search
 
 		if params.OrTerms {
 			queryParams["Terms"] = "(" + strings.Join(strings.Fields(terms), " | ") + ")" + excludeClause
+		} else if strings.HasPrefix(terms, `"`) && strings.HasSuffix(terms, `"`) {
+			queryParams["Terms"] = "(" + strings.Join(strings.Fields(terms), " <-> ") + ")" + excludeClause
 		} else {
 			queryParams["Terms"] = "(" + strings.Join(strings.Fields(terms), " & ") + ")" + excludeClause
 		}