Reinstate the ibm--z pictogram in carbon-website

[tay1orjones]

In carbon-design-system/carbon#18391 the ibm--z pictogram artwork was updated and removed from the deprecated list. This pictogram needs to be reinstated on carbon-website by editing the areas where it's been hidden.

carbon-website/src/components/SVGLibraries/PictogramLibrary/PictogramCategory.js

Lines 19 to 25 in f193125

	const hiddenPictograms = [
	'ibm--z',
	'ibm--z--partition',
	'ibm--z-and-linuxone-multi-frame',
	'ibm--z-and-linuxone-single-frame',
	'tokyo--volcano',
	];