Fix | Invalid transaction exception against the connections and distributed transactions

[DavoudEshtehari]

Unsubscribing from a transaction completion event before returning it to the pool is done to prevent potential signals from the previous state.

Fixes #1675

[codecov]

Codecov Report

Attention: 34 lines in your changes are missing coverage. Please review.

Comparison is base (b12b15d) 72.57% compared to head (8df5a34) 72.50%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
...c/Microsoft/Data/SqlClient/TdsParserStateObject.cs	86.04%	30 Missing ⚠️
...osoft/Data/SqlClient/TdsParserStateObject.netfx.cs	88.46%	3 Missing ⚠️
...oft/Data/SqlClient/TdsParserStateObject.netcore.cs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2301      +/-   ##
==========================================
- Coverage   72.57%   72.50%   -0.08%     
==========================================
  Files         310      310              
  Lines       62065    61873     -192     
==========================================
- Hits        45041    44858     -183     
+ Misses      17024    17015       -9     

Flag	Coverage Δ
addons	92.88% <ø> (ø)
netcore	76.70% <86.58%> (-0.02%)	⬇️
netfx	69.94% <87.15%> (-0.02%)	⬇️

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