fix(x-mp): 移除无用的 css 变量 --status-bar-height

[chouchouji]

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[github-actions]

Size report

Path	Size
packages/size-check/dist/size-check.es.js	47.2 KB (0%)
packages/size-check/dist/style.css	2.82 KB (0%)
packages/uni-app/dist/uni-app.es.js	2.52 KB (0%)
packages/uni-h5-vue/dist/vue.runtime.esm.js	76.41 KB (0%)
packages/uni-mp-vue/dist/vue.runtime.esm.js	43.22 KB (0%)
packages/uni-mp-alipay/dist/uni.api.esm.js	14.82 KB (0%)
packages/uni-mp-alipay/dist/uni.mp.esm.js	8.04 KB (0%)
packages/uni-mp-baidu/dist/uni.api.esm.js	11.33 KB (0%)
packages/uni-mp-baidu/dist/uni.mp.esm.js	9.68 KB (0%)
packages/uni-mp-qq/dist/uni.api.esm.js	10.65 KB (0%)
packages/uni-mp-qq/dist/uni.mp.esm.js	7.6 KB (0%)
packages/uni-mp-toutiao/dist/uni.api.esm.js	10.47 KB (0%)
packages/uni-mp-toutiao/dist/uni.mp.esm.js	9.42 KB (0%)
packages/uni-mp-weixin/dist/uni.api.esm.js	11.65 KB (0%)
packages/uni-mp-weixin/dist/uni.mp.esm.js	8.16 KB (0%)
packages/uni-quickapp-webview/dist/uni.api.esm.js	10.6 KB (0%)
packages/uni-quickapp-webview/dist/uni.mp.esm.js	8.16 KB (0%)