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
r_gl_type = GL_UNSIGNED_BYTE;
				r_compressed = true;
			} else {
				need_decompress = true;
			}
			decompress_ra_to_rg = true;
		} break;
		default: {
			ERR_FAIL_V_MSG(Ref<Image>(), "Image Format: " + itos(p_format) + " is not supported by the OpenGL3 Renderer");
		}
	}
	if (need_decompress || p_force_decompress) {
		if (!image.is_null()) {
			image = image->duplicate();
			image->decompress();
			ERR_FAIL_COND_V(image->is_compressed(), image);
			if (decompress_ra_to_rg) {
				image->convert_ra_rgba8_to_rg();
				image->convert(Image::FORMAT_RG8);
			}
			switch (image->get_format()) {
				case Image::FORMAT_RG8: {
					r_gl_format = GL_RG;
					r_gl_internal_format = GL_RG8;
					r_gl_type = GL_UNSIGNED_BYTE;
					r_real_format = Image::FORMAT_RG8;
					r_compressed = false;
				} break;
				case Image::FORMAT_RGB8: {
					r_gl_format = GL_RGB;