Image component renders img tag with empty class attribute if className prop is not passed and responsive=true

[wesleybl]

Describe the bug
If the className prop is not passed and the responsive prop is false (default), the @plone/volto/components/theme/Image/Image/Image component renders an img tag with an empty class attribute. That is:

<img src="src" class />

To Reproduce
Steps to reproduce the behavior:

1. Edit the View component in volto/packages/volto/src/components/manage/Blocks/Image/View.jsx, removing the className and responsive props passed to the Image component. Here:

volto/packages/volto/src/components/manage/Blocks/Image/View.jsx

Lines 31 to 71 in dd35efb

	<Image
	className={cx({
	'full-width': data.align === 'full',
	large: data.size === 'l',
	medium: data.size === 'm',
	small: data.size === 's',
	})}
	item={
	data.image_scales
	? {
	'@id': data.url,
	image_field: data.image_field,
	image_scales: data.image_scales,
	}
	: undefined
	}
	src={
	data.image_scales
	? undefined
	: isInternalURL(data.url)
	? // Backwards compat in the case that the block is storing the full server URL
	(() => {
	if (data.size === 'l')
	return `${flattenToAppURL(data.url)}/@@images/image`;
	if (data.size === 'm')
	return `${flattenToAppURL(
	data.url,
	)}/@@images/image/preview`;
	if (data.size === 's')
	return `${flattenToAppURL(
	data.url,
	)}/@@images/image/mini`;
	return `${flattenToAppURL(data.url)}/@@images/image`;
	})()
	: data.url
	}
	sizes={config.blocks.blocksConfig.image.getSizes(data)}
	alt={data.alt || ''}
	loading="lazy"
	responsive={true}
	/>

2. Create a page with an Image block and save it with an image.
3. Inspect the resulting img tag code.

Expected behavior
The img tag must not have a class attribute.

Software (please complete the following information):

• OS: Ubuntu
• Browser: Chrome
• Volto Version 18.9.1
• Plone Version 6.1.0