UI: Swap mq and hq NVENC Preset mappings

The old preset "mq" was "Max Quality", which used the old HQ preset with
two-pass enabled. The old preset "hq" was "Quality", which used the old
HQ preset without two-pass. Of the two, "mq" would have been considered
"slower" or "higher quality" than "hq", so let's swap these entries.
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Gitea Version: 1.28.0+dev-477-g8b6ad49a5f