Backend/FeeRateEstimation: refactor (def priority) #3773

Job	Run time
linux-github--dotnet-and-mono	3m 45s
linux-vanilla--newmono-only	8m 56s
linux-github--dotnet-and-newmono	7m 29s
linux-vanilla--stockdotnet6-and-newmono	6m 18s
linux-vanilla--stockdotnet6-and-stockmono	7m 16s
linux-vanilla--stockdotnet6-only	6m 30s
linux-vanilla--stockmono-only	5m 45s
macOS--dotnet6-and-mono	14m 39s
macOS--dotnet6-only	4m 2s
macOS--mono-only	11m 10s
windows--dotnet6-and-legacyFramework	6m 57s
windows--dotnet6-only	5m 48s
windows--legacyFramework-only	13m 43s
conventions	2m 9s
snap_pkg	7m 22s
snap_pkg_beta	7m 34s
	1h 59m 23s

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