network: handle stream creation on existing conns

[algorandskiy]

Summary

1. TestP2PNetworkDHTCapabilities failure (and TestCapabilities_Varying failure) showed the following race:

   1. DHT creates connection faster than our dialer
   2. That conn is not being marked so Connected does not create a stream

   Fixed by calling handleConnected directly and splitting peerID and direction checks - for direct call these might prevent from stream establishing.

2. Changed Read to ReadFull in p2p metadata exchange code in order to workaround possible p2p transport level fragmentation for remote nodes.

3. Updated streamManager.streams maps clean up - now it should not have any stale (reset or abandoned streams)

4. While testing with DHT enabled, found it can consume all conns fast and lot letting regular conns to get through. It gets fixes eventually when the dialer will be trying active conns but takes longer. Bumped limits to GossipFanuot *3 when DHT is on.

Test Plan

Added new unit tests
Run both tests repeatedly to make sure no failures anymore

[codecov]

Codecov Report

❌ Patch coverage is 47.22222% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 47.80%. Comparing base (136b97a) to head (53b6108).
⚠️ Report is 2 commits behind head on master.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
network/p2p/streams.go	43.47%	13 Missing ⚠️
network/p2p/p2p.go	25.00%	6 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (136b97a) and HEAD (53b6108). Click for more details.

HEAD has 4 uploads less than BASE

Flag	BASE (136b97a)	HEAD (53b6108)
full_coverage	4	0

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #6572       +/-   ##
===========================================
- Coverage   63.53%   47.80%   -15.74%     
===========================================
  Files         486      646      +160     
  Lines       67821    88108    +20287     
===========================================
- Hits        43089    42116      -973     
- Misses      21143    43224    +22081     
+ Partials     3589     2768      -821     

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[gmalouf]

We should talk through the gossip fanout multiplier