[QGIS Server][WMS] GetLegend - WIDTH / HEIGHT parameters not taken into account

[vprint]

What is the bug or the crash?

WIDTH / HEIGHT parameters are not taken into account on WMS getLegend request.

Steps to reproduce the issue

Exemple : this request with WIDTH=864 / https://qwc2.sourcepole.ch/api/v1/legend/qwc_demo?VERSION=1.3.0&SERVICE=WMS&REQUEST=GetLegendGraphic&FORMAT=image%2Fpng&CRS=EPSG%3A3857&SLD_VERSION=1.1.0&SCALE=10000000&WIDTH=864&HEIGHT=986&BBOX=-143000%2C4695604.166666666%2C2143000%2C7304395.833333334&LAYER=geographic_lines

give the same output as this request with WIDTH=3864 : https://qwc2.sourcepole.ch/api/v1/legend/qwc_demo?VERSION=1.3.0&SERVICE=WMS&REQUEST=GetLegendGraphic&FORMAT=image%2Fpng&CRS=EPSG%3A3857&SLD_VERSION=1.1.0&SCALE=10000000&WIDTH=3864&HEIGHT=986&BBOX=-143000%2C4695604.166666666%2C2143000%2C7304395.833333334&LAYER=geographic_lines

Versions

qgis 3.34

Supported QGIS version

• [ ] I'm running a supported QGIS version according to the roadmap.

New profile

• [ ] I tried with a new QGIS profile

Additional context

No response

[elpaso]

Duplicate of https://github.com/qgis/QGIS/issues/38706