[7.0.2 Cherry-pick] Fix SqlCommand.Cancell null ref exception

[github-actions]

Cherry-pick of #4372 (6a0153a) into release/7.0.

[paulmedynski]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.71%. Comparing base (4a37600) to head (edc5144).
⚠️ Report is 3 commits behind head on release/7.0.

❗ There is a different number of reports uploaded between BASE (4a37600) and HEAD (edc5144). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (4a37600)	HEAD (edc5144)
CI-SqlClient	1	0

Additional details and impacted files

@@               Coverage Diff               @@
##           release/7.0    #4373      +/-   ##
===============================================
- Coverage        75.05%   65.71%   -9.35%     
===============================================
  Files              280      275       -5     
  Lines            43856    65883   +22027     
===============================================
+ Hits             32918    43292   +10374     
- Misses           10938    22591   +11653     

Flag	Coverage Δ
CI-SqlClient	?
PR-SqlClient-Project	65.71% <100.00%> (?)

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