Unsubscribe from broker on service stop

[soffokl]

On service restart, we were keeping old subscriptions to the broker.
Closes: #1616

[codecov-io]

Codecov Report

Merging #1794 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1794      +/-   ##
==========================================
+ Coverage   46.78%   46.79%   +0.01%     
==========================================
  Files         281      281              
  Lines       11574    11575       +1     
==========================================
+ Hits         5415     5417       +2     
+ Misses       5735     5733       -2     
- Partials      424      425       +1

Impacted Files	Coverage Δ
communication/nats/dialog/dialog_waiter.go	86.11% <100%> (+0.19%)	⬆️
tequilapi/sse/sse.go	68.88% <0%> (-2.23%)	⬇️
core/discovery/discovery.go	66.38% <0%> (+0.84%)	⬆️
session/pingpong/invoice_payer.go	80.85% <0%> (+1.41%)	⬆️

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