Fix depth texture being incorrectly affected by swap table

[Tilka]

This fixes issue 13734: "Z-textures are incorrectly affected by swaptable". This was reported by @fadedled, who presumably noticed this while working on Seta GX.

I've not hardware-tested this myself beyond running the repro case using the hardware fifoplayer.

[iwubcode]

If this is true, it would help to add a fifo to the builder to ensure we maintain this? @JMC47

[JMC47]

Added the test.

[iwubcode]

@Tilka - is this ready to go or do you plan on hardware testing it first?

[Tilka]

is this ready to go or do you plan on hardware testing it first?

I don't think I'll get around to doing more detailed hardware tests.

[dolphin-ci]

FifoCI detected that this change impacts graphical rendering. Here are the behavior differences detected by the system:

• zbuff-test on ogl-lin-mesa: diff
• zbuff-test on mvk-osx-m1: diff
• zbuff-test on mtl-osx-m1: diff

_{^{automated-fifoci-reporter}}