Use the fast vector highlighter for highlighting search results

services/search/pkg/opensearch/backend.go

@@ -115,7 +115,9 @@ func (b *Backend) Search(ctx context.Context, sir *searchService.SearchIndexRequ
 				PreTags:  []string{"<mark>"},
 				PostTags: []string{"</mark>"},
 				Fields: map[string]osu.BodyParamHighlight{
-					"Content": {},
+					"Content": {
+						Type: "fvh",
+					},
 				},
 			},
 		},

services/search/pkg/opensearch/internal/osu/request.go

@@ -43,6 +43,7 @@ func (q QueryReqBody[O]) MarshalJSON() ([]byte, error) {
 type BodyParamHighlight struct {
 	PreTags  []string                      `json:"pre_tags,omitempty"`
 	PostTags []string                      `json:"post_tags,omitempty"`
+	Type     string                        `json:"type,omitempty"`
 	Fields   map[string]BodyParamHighlight `json:"fields,omitempty"`
 }