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
ERR_FAIL_COND(rt->sdf_texture_write_fb != 0);
	Size2i size = _render_target_get_sdf_rect(rt).size;
	glGenTextures(1, &rt->sdf_texture_write);
	glActiveTexture(GL_TEXTURE0);
	glBindTexture(GL_TEXTURE_2D, rt->sdf_texture_write);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, size.width, size.height, 0, GL_RED, GL_UNSIGNED_BYTE, nullptr);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 1);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glGenFramebuffers(1, &rt->sdf_texture_write_fb);
	glBindFramebuffer(GL_FRAMEBUFFER, rt->sdf_texture_write_fb);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, rt->sdf_texture_write, 0);
	int scale;
	switch (rt->sdf_scale) {
		case RS::VIEWPORT_SDF_SCALE_100_PERCENT: {
			scale = 100;
		} break;
		case RS::VIEWPORT_SDF_SCALE_50_PERCENT: {
			scale = 50;