QGB better e2e context and channel usage

[rach-id]

• Better usage of context (no more gymnastics)
• Usage of two channels to organize communication between multiple go routines

Closes #522

[codecov-commenter]

Codecov Report

Merging #562 (05afd4a) into qgb-integration (3b3176c) will decrease coverage by 0.05%.
The diff coverage is 0.00%.

@@                Coverage Diff                 @@
##           qgb-integration    #562      +/-   ##
==================================================
- Coverage             9.63%   9.58%   -0.06%     
==================================================
  Files                   55      55              
  Lines                 9401    9456      +55     
==================================================
  Hits                   906     906              
- Misses                8416    8471      +55     
  Partials                79      79              

Impacted Files	Coverage Δ
e2e/qgb/qgb_network.go	0.00% <0.00%> (ø)
e2e/qgb/test_commons.go	0.00% <0.00%> (ø)

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