Regression from #71248:

I believe this pull may have caused errors on WebGL since it moves the `GLES_OVER_GL` guard. WebGL does not support texture swizzling per: https://registry.khronos.org/webgl/specs/latest/2.0/#5.19
so this is causing the following trace in Chrome:
```
WebGL: INVALID_ENUM: texParameter: invalid parameter name
```
and it quickly fills up the 256 log limit for the same message in WebGL.

This doesn't appear to be breaking anything asides from causing the numerous log messages.

_Originally posted by @jnlopar in https://github.com/godotengine/godot/issues/71248#issuecomment-1384768973_

CC @rsjtdrjgfuzkfg @clayjohn
Texture *texture = texture_owner.get_or_null(p_texture);
	ERR_FAIL_COND_V(!texture, Ref<Image>());
#ifdef TOOLS_ENABLED
	if (texture->image_cache_2d.is_valid() && !texture->is_render_target) {
		return texture->image_cache_2d;
	}
#endif
#ifdef GLES_OVER_GL
	
	
	Vector<uint8_t> data;
	int data_size = Image::get_image_data_size(texture->alloc_width, texture->alloc_height, texture->real_format, texture->mipmaps > 1);
	data.resize(data_size * 2); 
	uint8_t *w = data.ptrw();
	glActiveTexture(GL_TEXTURE0);
	glBindTexture(texture->target, texture->tex_id);
	glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);
	for (int i = 0; i < texture->mipmaps; i++) {
		int ofs = Image::get_image_mipmap_offset(texture->alloc_width, texture->alloc_height, texture->real_format, i);
		if (texture->compressed) {
			glPixelStorei(GL_PACK_ALIGNMENT, 4);
			glGetCompressedTexImage(texture->target, i, &w[ofs]);
		} else {
			glPixelStorei(GL_PACK_ALIGNMENT, 1);
			glGetTexImage(texture->target, i, texture->gl_format_cache, texture->gl_type_cache, &w[ofs]);
		}
	}
	data.resize(data_size);
	ERR_FAIL_COND_V(data.size() == 0, Ref<Image>());
	Ref<Image> image = Image::create_from_data(texture->width, texture->height, texture->mipmaps > 1, texture->real_format, data);