Patch memory leak with subscriptions when client abruptly terminates

[Shane32]

See:

• Probable memory leak in WebSocketReaderPipeline #667
• GraphQL Subscription does not close sockets to Load Balancer #621

[codecov-commenter]

Codecov Report

Merging #668 (d67b0fa) into master (db8484f) will not change coverage.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           master     #668   +/-   ##
=======================================
  Coverage   54.86%   54.86%           
=======================================
  Files          64       64           
  Lines        1582     1582           
  Branches      158      158           
=======================================
  Hits          868      868           
  Misses        660      660           
  Partials       54       54           

Impacted Files	Coverage Δ
...ubscriptions.WebSockets/WebSocketReaderPipeline.cs	0.00% <0.00%> (ø)

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[Shane32]

@sungam3r I'm going to merge this so it is testable via GitHub Packages. Please let me know if you have any comments and I can make changes.

[Shane32]

Basically, the only change here is to move the if condition inside the try block, so the finally block executes regardless of the websocket state.

[Shane32]

(The finally block terminating the dataflow)

[sungam3r]

ok