build: Remove Nuget.Restore.targets #2558

Job	Run time
macOS--dotnet6-only	7m 31s
macOS--dotnet6-and-mono	9m 24s
macOS--mono-only	15m 36s
linux22-github--dotnet-and-mono	3m 42s
windows--dotnet6-and-legacyFramework	6m 59s
windows--dotnet6-only	6m 29s
linux22-github--dotnet-and-newmono	4m 19s
linux22-vanilla--stockmono-only	1m 23s
linux22-vanilla--stockdotnet6-and-newmono	7m 52s
windows--legacyFramework-only	13m 6s
linux22-vanilla--newmono-only	10m 29s
linux22-vanilla--stockdotnet6-and-stockmono	5m 39s
linux22-vanilla--stockdotnet6-only	5m 17s
linux20-github--dotnet-and-mono	3m 50s
linux20-github--dotnet-and-newmono	5m 5s
linux20-vanilla--newmono-only	9m 55s
linux20-vanilla--stockmono-only	2m 23s
conventions	0s
snap_pkg	0s
	1h 58m 59s

Provide feedback