Backend(,Tests): stop using binary serialization #3027

Job	Run time
linux-vanilla--stockdotnet6-and-newmono	2m 44s
linux-vanilla--newmono-only	4m 23s
linux-github--dotnet-and-mono	3m 36s
linux-github--dotnet-and-newmono	4m 41s
linux-vanilla--stockdotnet6-only	2m 3s
linux-vanilla--stockdotnet6-and-stockmono	2m 50s
linux-vanilla--stockmono-only	2m 59s
macOS--dotnet6-and-mono	18m 58s
macOS--dotnet6-only	6m 0s
macOS--mono-only	7m 20s
windows--dotnet6-and-legacyFramework	3m 39s
windows--dotnet6-only	3m 42s
windows--legacyFramework-only	14m 15s
conventions	0s
snap_pkg	0s
snap_pkg_beta	0s
	1h 17m 10s

Provide feedback