sln: remove fsdk nested proj from solution #2796

Job	Run time
linux-github--dotnet-and-newmono	8m 51s
linux-vanilla--newmono-only	9m 57s
linux-github--dotnet-and-mono	4m 45s
linux-vanilla--stockdotnet6-and-newmono	6m 34s
linux-vanilla--stockdotnet6-and-stockmono	7m 30s
linux-vanilla--stockdotnet6-only	5m 24s
linux-vanilla--stockmono-only	7m 50s
macOS--dotnet6-and-mono	14m 19s
macOS--dotnet6-only	5m 59s
macOS--mono-only	18m 14s
windows--dotnet6-and-legacyFramework	10m 46s
windows--dotnet6-only	7m 46s
windows--legacyFramework-only	13m 47s
conventions	1m 36s
snap_pkg	7m 45s
	2h 11m 3s

Provide feedback