fix: Fix bug for parsing expression that include quotes (#28416)

issue: #28365 
Fix bug for parsing error when a string enclosed in single quotes in an
expression contains multiple double quotes.
such as:
```
expr = "tag == '\"blue\"'"
```

Signed-off-by: Cai Zhang <cai.zhang@zilliz.com>

internal/datacoord/index_builder.go

@@ -191,7 +191,7 @@ func (ib *indexBuilder) run() {
 	for _, buildID := range buildIDs {
 		ok := ib.process(buildID)
 		if !ok {
-			log.Ctx(ib.ctx).Info("there is no IndexNode available or etcd is not serviceable, wait a minute...")
+			log.Ctx(ib.ctx).Info("there is no idle indexing node, wait a minute...")
 			break
 		}
 	}

internal/parser/planparserv2/plan_parser_v2_test.go

@@ -934,6 +934,7 @@ func Test_EscapeString(t *testing.T) {
 		`str2 like 'abc"def-%'`,
 		`str4 like "abc\367-%"`,
 		`str4 like "中国"`,
+		`tag == '"blue"'`,
 	}
 	for _, expr = range exprs {
 		_, err = CreateSearchPlan(schema, expr, "FloatVectorField", &planpb.QueryInfo{

internal/parser/planparserv2/utils.go

@@ -503,7 +503,7 @@ func convertEscapeSingle(literal string) (string, error) {
 			b.WriteString(literal[start : end-1])
 			b.WriteString(`'`)
 		}
-		start = end
+		start = end + 1
 	}
 	b.WriteString(literal[end+1 : len(literal)-1])
 	b.WriteString(`"`)

internal/parser/planparserv2/utils_test.go

@@ -187,6 +187,13 @@ func Test_convertEscapeSingle(t *testing.T) {
 		{`"\\\\'"`, `\\'`},
 		{`"\\\\\'"`, `\\'`},
 		{`'"'`, `"`},
+		{`'""'`, `""`},
+		{`'"""'`, `"""`},
+		{`'"\""'`, `"""`},
+		{`'a"b\"c\\"d'`, `a"b"c\"d`},
+		{`"a\"b\"c\\\"d"`, `a"b"c\"d`},
+		{`'A "test"'`, `A "test"`},
+		{`"A \"test\""`, `A "test"`},
 		{`'\"'`, `"`},
 		{`'\\"'`, `\"`},
 		{`'\\\"'`, `\"`},