[Test] Remove deprecated Stylelint rule

.stylelintrc.json

@@ -20,7 +20,6 @@
         "color-hex-length": null,
         "comment-empty-line-before": null,
         "media-feature-range-notation": "prefix",
-        "number-leading-zero": null,
         "property-no-vendor-prefix": null,
         "rule-empty-line-before": null,
         "value-no-vendor-prefix": null