Fix problem when restarting right after debugging

[rchiodo]

Fixes #10741

I don't think this was an actual regression, but rather a papercut. Super easy fix though.

[codecov-commenter]

Codecov Report

Merging #10783 (dda78b9) into main (708004b) will decrease coverage by 0%.
The diff coverage is 69%.

❗ Current head dda78b9 differs from pull request most recent head 4289265. Consider uploading reports for the commit 4289265 to get more accurate results

@@          Coverage Diff           @@
##            main   #10783   +/-   ##
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- Coverage     62%      62%   -1%     
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  Files        476      476           
  Lines      33048    33058   +10     
  Branches    5387     5391    +4     
======================================
- Hits       20736    20733    -3     
- Misses     10274    10279    +5     
- Partials    2038     2046    +8     

Impacted Files	Coverage Δ
src/kernels/debugger/kernelDebugAdapterBase.ts	76% <56%> (-3%)	⬇️
...active-window/debugger/jupyter/debuggingManager.ts	63% <100%> (+<1%)	⬆️
...tive-window/debugger/jupyter/kernelDebugAdapter.ts	58% <100%> (ø)
src/notebooks/debugger/debuggingManager.ts	53% <100%> (+<1%)	⬆️
src/platform/common/cancellation.ts	64% <0%> (-4%)	⬇️
src/platform/telemetry/telemetry.ts	76% <0%> (-4%)	⬇️
.../kernels/raw/launcher/kernelEnvVarsService.node.ts	68% <0%> (-3%)	⬇️
...form/common/process/pythonExecutionFactory.node.ts	73% <0%> (-3%)	⬇️
src/kernels/raw/session/rawSocket.node.ts	74% <0%> (-2%)	⬇️
...ommon/process/environmentActivationService.node.ts	71% <0%> (-1%)	⬇️
... and 3 more

[DonJayamanne]

I think we should move this property initialization to the very top (just after checking it), else this method disconnect can be called multiple times and we could end up sending multiple disconnect requests

[rchiodo]

Ah good point.

[DonJayamanne]

One suggested change to prevent duplicate disconnect requests being sent out