Cancel cell task when closing related cell doc

[DonJayamanne]

For #5925

[IanMatthewHuff]

Ahh, that was a bad one. Nice fix.

[DonJayamanne]

Yes, very bad.

[codecov-commenter]

Codecov Report

Merging #5926 (47d58d0) into main (fdee9dc) will increase coverage by 0%.
The diff coverage is 66%.

@@          Coverage Diff          @@
##            main   #5926   +/-   ##
=====================================
  Coverage     72%     72%           
=====================================
  Files        404     404           
  Lines      27086   27086           
  Branches    3956    3957    +1     
=====================================
+ Hits       19509   19530   +21     
+ Misses      5945    5902   -43     
- Partials    1632    1654   +22     

Impacted Files	Coverage Δ
...lient/datascience/jupyter/kernels/cellExecution.ts	70% <66%> (ø)
...t/datascience/jupyter/jupyterInvalidKernelError.ts	66% <0%> (-34%)	⬇️
src/client/logging/logger.ts	52% <0%> (-18%)	⬇️
src/client/datascience/commands/serverSelector.ts	86% <0%> (-14%)	⬇️
src/client/datascience/kernel-launcher/types.ts	48% <0%> (-8%)	⬇️
src/client/datascience/liveshare/liveshare.ts	75% <0%> (-7%)	⬇️
src/client/activation/activationManager.ts	53% <0%> (-5%)	⬇️
...t/datascience/notebook/vscodeNotebookController.ts	77% <0%> (-5%)	⬇️
src/client/logging/transports.ts	76% <0%> (-5%)	⬇️
src/client/datascience/datascience.ts	91% <0%> (-5%)	⬇️
... and 34 more

[grudloff]

Hello! This should fix issue #5877?

[DonJayamanne]

Oh yes, sorry, I'll update the change log