Fix bleve fuzziness (#30799)

Fix #30797
Fix #30317

modules/indexer/internal/bleve/util.go

@@ -47,3 +47,15 @@ func openIndexer(path string, latestVersion int) (bleve.Index, int, error) {
 
 	return index, 0, nil
 }
+
+func GuessFuzzinessByKeyword(s string) int {
+	// according to https://github.com/blevesearch/bleve/issues/1563, the supported max fuzziness is 2
+	// magic number 4 was chosen to determine the levenshtein distance per each character of a keyword
+	// BUT, when using CJK (eg: `갃갃갃` `啊啊啊`), it mismatches a lot.
+	for _, r := range s {
+		if r >= 128 {
+			return 0
+		}
+	}
+	return min(2, len(s)/4)
+}