Fix: Always release HttpContent

[oriolbellet]

Potential leak found in HttpClientResponseHandler class. httpContent.release is not called if a Runtime exception is thrown before releasing the object.

Moved HttpContent.release call to a finally block based on following netty documentation ("Inbound messages" section): https://netty.io/wiki/reference-counted-objects.html

A couple of Integration tests were failing in master branch when run locally

[codecov]

Codecov Report

Merging #21 (83782a5) into master (f827887) will not change coverage.
The diff coverage is 84.61%.

@@            Coverage Diff            @@
##             master      #21   +/-   ##
=========================================
  Coverage     79.94%   79.94%           
  Complexity      964      964           
=========================================
  Files           118      118           
  Lines          3460     3460           
  Branches        315      315           
=========================================
  Hits           2766     2766           
  Misses          523      523           
  Partials        171      171           

Impacted Files	Coverage Δ	Complexity Δ
...http/netty/response/HttpClientResponseHandler.java	81.25% <84.61%> (ø)	27.00 <0.00> (ø)
...ng/platform/net/http/WebSocketListenerAdapter.java	66.66% <0.00%> (-16.67%)	4.00% <0.00%> (-1.00%)
...form/net/http/WebSocketMessageListenerAdapter.java	50.00% <0.00%> (+12.50%)	4.00% <0.00%> (+1.00%)

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