Backend(,Tests): don't marshall hybrid type names #2943

Job	Run time
linux20-github--dotnet-and-newmono	4m 6s
linux20-vanilla--stockmono-only	4m 45s
linux20-vanilla--newmono-only	5m 32s
linux20-github--dotnet-and-mono	3m 22s
linux22-github--dotnet-and-mono	3m 37s
linux22-github--dotnet-and-newmono	3m 32s
linux22-vanilla--newmono-only	5m 48s
linux22-vanilla--stockdotnet6-and-newmono	5m 40s
linux22-vanilla--stockdotnet6-and-stockmono	4m 48s
linux22-vanilla--stockdotnet6-only	4m 42s
linux22-vanilla--stockmono-only	5m 5s
macOS--dotnet6-and-mono	4m 38s
macOS--dotnet6-only	4m 23s
macOS--mono-only	6m 39s
windows--dotnet6-and-legacyFramework	6m 31s
windows--dotnet6-only	5m 31s
windows--legacyFramework-only	13m 17s
conventions	1m 21s
snap_pkg	0s
	1h 33m 17s

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