Upgrade blevesearch to v0.8.1 (#9177)

For #1441

https://github.com/blevesearch/bleve/commit/a91b427b59b893f112021841ba7370d285f8426f

vendor/github.com/blevesearch/bleve/index/index.go

@@ -121,6 +121,10 @@ type IndexReaderOnly interface {
 	FieldDictOnly(field string, onlyTerms [][]byte, includeCount bool) (FieldDict, error)
 }
 
+type IndexReaderContains interface {
+	FieldDictContains(field string) (FieldDictContains, error)
+}
+
 // FieldTerms contains the terms used by a document, keyed by field
 type FieldTerms map[string][]string
 
@@ -230,6 +234,10 @@ type FieldDict interface {
 	Close() error
 }
 
+type FieldDictContains interface {
+	Contains(key []byte) (bool, error)
+}
+
 // DocIDReader is the interface exposing enumeration of documents identifiers.
 // Close the reader to release associated resources.
 type DocIDReader interface {