Remove 'Accurate Geometry Shader' setting

[tywald]

This setting is currently set to be enabled by default and when disabled causes performance loss in games that use GS and can cause graphical glitches. There should be no instance where turning it off is beneficial so let's just remove the option to do so.

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This change is 

[Dragios]

I thought this was supposed to be Accurate Multiplication forced turned on and not Accurate Geometry Shader?

[FearlessTobi]

Can anyone test other games that use Geo shaders (e.g. Layton games) and check for performance differences?

[RocketRobz]

@Dragios Accurate Multiplication still crashes Citra for me, whenever 3D tries to be rendered, so that setting shouldn't be removed, if that's what you mean.

[tywald]

I thought this was supposed to be Accurate Multiplication forced turned on and not Accurate Geometry Shader?

While it's true the discussion on Discord was about Accurate Multiplication, I proposed a removal regarding Accurate Geometry Shader because I noticed when it's turned off for example in MH4U decreased the performance and would cause graphical glitches.

Since it's on by default I figured there is no reason to ever have it off.

[wwylele]

There is more code in gl_shader_gen and other files that can be deleted. But I guess this can be in a second PR

[zhaowenlan1779]

Codewise LGTM, but I'm wondering if there's any persuasive data/test that shows how this option has no impact on, or even improves performance? (Probably could use some #4882)

[wwylele]

Some internal testing indeed shows that disabling accurate GS doesn't help performance, and sometimes even make it worse. I am going to merge this after coordinating the server side change.