(fix) Add correct StartupWMClass for Debian

[joshgoebel]

If there is a build process that I should modify to change this JUST for Debian, please point me to it.

On Debian the WMClass is indeed `thorium-browser.

WM_NAME(UTF8_STRING) = "Comparing Alex313031:main...joshgoebel:patch-1 · Alex313031/thorium - Thorium"
_NET_WM_NAME(UTF8_STRING) = "Comparing Alex313031:main...joshgoebel:patch-1 · Alex313031/thorium - Thorium"
WM_WINDOW_ROLE(STRING) = "browser"
WM_CLASS(STRING) = "thorium-browser", "Thorium-browser"
_NET_WM_WINDOW_TYPE(ATOM) = _NET_WM_WINDOW_TYPE_NORMAL

[primobrowser]

@joshgoebel Good work.

But there are a few more .desktop files that need this. I will edit this and then merge it when I'm ready to start M132

[Alex313031]

@joshgoebel Wow OK that was my work github. This is my public github. I meant to comment as Alex313031.
But uh, yeah, I guess you know where I work now lol.