[Bug] The `axisLabel.height` property does not take effect when no background color is set

[xxxx-p]

Version

6.0.0

Link to Minimal Reproduction

https://echarts.apache.org/examples/zh/editor.html?code=PYBwLglsB2AEC8sDeAoWsDGwA2wBOAXLANoBEAxAMyUCcAHACIBCpAugDRqxjA6QhFU6dGDwQA5uICmhWKQCGADwgBnUp2GwlqgArAI0MDMFdNYAJ4gpRUioAW8gCbAA7qVOwAvl08bY4sUdBXy5FAEFlFSJiIWELKxsMeSNxfHN1D0dk-WjSAFkYdTkAFQBXKSLSAHUpR0riu1LKgDExSoBlZI7S6DYfDi5zCNVo2JFLazkAN3lscvd0TwH0FRkIKSiSMdhoeQBbSdJAF7dAUuNAfujAO9SMswmbACN5PGvhB7wqiEcwOxsANgAGACkz3QWTAORIAEY_uxYABWABMMPhf2hsGoABYYbRUdRUfDkax-ihPEA&_source=echarts-doc-preview

Steps to Reproduce

1. Create a regular bar chart
2. Set the height of the axis label without setting the background color

Current Behavior

option: option = {
color: ["#3398DB"],
tooltip: {
trigger: "axis",
axisPointer: {
type: "shadow"
}
},
grid: {},
xAxis: [{
type: "category",
data: ["Mo", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"],
axisLabel: {
height: 150
}
}],
yAxis: [{
type: "value"
}],
series: [{
name: "直接访问",
type: "bar",
barWidth: "60%",
data: [10, 52, 200, 334, 390, 330, 220]
}]
}

Expected Behavior

option: option = {
color: ["#3398DB"],
tooltip: {
trigger: "axis",
axisPointer: {
type: "shadow"
}
},
grid: {},
xAxis: [{
type: "category",
data: ["Mo", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"],
axisLabel: {
height: 150,
backgroundColor: 'red'
}
}],
yAxis: [{
type: "value"
}],
series: [{
name: "直接访问",
type: "bar",
barWidth: "60%",
data: [10, 52, 200, 334, 390, 330, 220]
}]
}

Environment

- OS: mac os
- Browser: chrome

Any additional comments?

No response

[plainheart]

This is a known behavior("issue"), but it was intentionally designed this way from the outset — likely for performance reasons, the background box will not be rendered if no explicit backgroundColor is specified.

As a workaround, you can explicitly set a transparent color (e.g., 'transparent' or 'rgba(0,0,0,0)').

[xxxx-p]

这是一个已知行为（“问题”），但从一开始就是故意这样设计的——可能是出于性能原因，如果没有明确指定 backgroundColor，则不会渲染背景框。

作为一种变通方法，您可以显式地设置透明颜色（例如，'transparent'或'rgba(0,0,0,0)'）。

Thank you