Backend(,Tests): stop using binary serialization #3020

Job	Run time
linux-github--dotnet-and-newmono	2m 50s
linux-github--dotnet-and-mono	1m 54s
linux-vanilla--newmono-only	4m 21s
linux-vanilla--stockdotnet6-and-newmono	2m 44s
linux-vanilla--stockdotnet6-and-stockmono	2m 58s
linux-vanilla--stockdotnet6-only	2m 4s
linux-vanilla--stockmono-only	2m 57s
macOS--dotnet6-and-mono	7m 2s
macOS--dotnet6-only	2m 23s
macOS--mono-only	8m 59s
windows--dotnet6-and-legacyFramework	3m 2s
windows--dotnet6-only	3m 38s
windows--legacyFramework-only	11m 56s
conventions	0s
snap_pkg	0s
snap_pkg_beta	0s
	56m 48s

Provide feedback