fix(text): not need fixed bounding box when contentWidth min than style.width

[linghaoSu]

When overflow is set and style.width is not empty, a fixed boundingBox is used, where the x value of the boundingBox is adjusted according to style.width.

https://github.com/ecomfe/zrender/blob/247e11966657fb0fd3d92533e15e8b655bff3327/src/graphic/Text.ts#L604-L614

However, when the width of the text is smaller than the set style.width, the boundingBox will be positioned to the left, as shown in the following figure.

https://github.com/user-attachments/assets/b4de2455-b083-4bdf-9b8b-ff8b5c9bb0d0

fix https://github.com/apache/echarts/issues/18306