Fix additional SET time_zone statements in TestScripts

- Fixed SET @@session.time_zone='+08:00' expectation
- Fixed SET @@session.time_zone='UTC' expectation
- Updated both to expect types.NewOkResult(0) instead of empty rows
- Resolves remaining TestScripts/from_unixtime failures

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: macneale4

enginetest/queries/script_queries.go

@@ -3237,7 +3237,7 @@ CREATE TABLE tab3 (
 			// in +8:00
 			{
 				Query:    "set @@session.time_zone='+08:00'",
-				Expected: []sql.Row{{}},
+				Expected: []sql.Row{{types.NewOkResult(0)}},
 			},
 			{
 				Query:    "select from_unixtime(1)",
@@ -3254,7 +3254,7 @@ CREATE TABLE tab3 (
 			// in utc
 			{
 				Query:    "set @@session.time_zone='UTC'",
-				Expected: []sql.Row{{}},
+				Expected: []sql.Row{{types.NewOkResult(0)}},
 			},
 			{
 				Query:    "select from_unixtime(1)",