fix: Subscription source bugs fix

[kuznetsss]

For #1620.

• Add timeouts for websocket operations for connections to rippled. Without these timeouts if connection hangs for some reason, clio wouldn't know the connection is hanging.
• Fix potential data race in choosing new subscription source which will forward messages to users.
• Optimise switching between subscription sources.

[cindyyan317]

👍 I think the data race problem is solved.
Only want to double check the timeout value.

[godexsoft]

Just a little style nit. And of course the crashing test needs to be fixed but frankly it's not possible to tell why it would fail just by looking at the code.. good luck 🤞

[codecov]

Codecov Report

Attention: Patch coverage is 86.20690% with 4 lines in your changes missing coverage. Please review.

Project coverage is 67.83%. Comparing base (2e2740d) to head (fbb55d6).
Report is 1 commits behind head on release/2.2.3.

Files with missing lines	Patch %	Lines
src/etl/impl/SubscriptionSource.cpp	87.50%	0 Missing and 2 partials ⚠️
src/etl/LoadBalancer.cpp	88.88%	1 Missing ⚠️
src/util/requests/impl/WsConnectionImpl.hpp	75.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@                Coverage Diff                @@
##           release/2.2.3    #1626      +/-   ##
=================================================
+ Coverage          67.80%   67.83%   +0.03%     
=================================================
  Files                234      234              
  Lines               9451     9463      +12     
  Branches            5271     5277       +6     
=================================================
+ Hits                6408     6419      +11     
- Misses              1653     1654       +1     
  Partials            1390     1390              

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[godexsoft]

👍