fix(query): change default format_null_as_str to false (#18026)

Author: everpcpc

src/common/io/src/format_settings.rs

@@ -34,7 +34,7 @@ impl Default for FormatSettings {
             jiff_timezone: TimeZone::UTC,
             geometry_format: GeometryDataType::default(),
             enable_dst_hour_fix: false,
-            format_null_as_str: true,
+            format_null_as_str: false,
         }
     }
 }

src/query/settings/src/settings_default.rs

@@ -1116,7 +1116,7 @@ impl DefaultSettings {
                     range: Some(SettingRange::Numeric(0..=1)),
                 }),
                 ("format_null_as_str", DefaultSettingValue {
-                    value: UserSettingValue::UInt64(1),
+                    value: UserSettingValue::UInt64(0),
                     desc: "Format NULL as str in query api response",
                     mode: SettingMode::Both,
                     scope: SettingScope::Both,