Go: add context (#17314)

### Summary

As title.

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

internal/parser/parser/office_parsers_nocgo_test.go

@@ -9,7 +9,7 @@ import (
 )
 
 func TestOfficeParsers_ParseWithResult_NoCGO(t *testing.T) {
-	ctx := context.Background()
+	ctx := t.Context()
 	cases := []struct {
 		name string
 		res  ParseResult

internal/parser/parser/pdf_parser_nocgo_test.go

@@ -9,9 +9,8 @@ import (
 )
 
 func TestPDFParser_ParseWithResult_NoCGO(t *testing.T) {
-	ctx := context.Background()
 	pdf := NewPDFParser()
-
+	ctx := t.Context()
 	empty := pdf.ParseWithResult(ctx, "empty.pdf", nil)
 	if empty.Err != nil {
 		t.Fatalf("empty input: want nil err, got %v", empty.Err)