Merge | Move ReliabilitySection / BestEffortCleanup to framework specific files

[MichelZ]

I don't think we want to wrap those in #IF NETFRAMEWORK / NETCORE conditional compiles, it makes sense to have them in their own files, so I've moved them out of the "future-common-project" file(s)

Part of #2953

[codecov]

Codecov Report

Attention: Patch coverage is 37.03704% with 34 lines in your changes missing coverage. Please review.

Project coverage is 72.67%. Comparing base (1b9df10) to head (f97eaf4).
Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
...fx/src/Microsoft/Data/SqlClient/TdsParser.netfx.cs	39.21%	31 Missing ⚠️
.../src/Microsoft/Data/SqlClient/TdsParser.netcore.cs	0.00%	3 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #2984 +/- ##
==========================================
+ Coverage 72.64% 72.67% +0.02% 
==========================================
Files 285 286 +1 Lines 59160 59160 ==========================================
+ Hits 42979 42995 +16 + Misses 16181 16165 -16 

Flag	Coverage Δ
addons	92.58% <ø> (ø)
netcore	75.44% <0.00%> (+0.05%)	⬆️
netfx	71.07% <39.21%> (-0.02%)	⬇️

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[benrr101]

Overall I think this makes sense and is probably a good idea. Still not a huge fan of the conditional attribute, but since it's already there, I won't raise a fuss :)

[benrr101]

@MichelZ if you can resolve the conflict, I can get this merged 🚢

[MichelZ]

@benrr101 Done! Thx