[fix][prometheusexporter] Race condition between start and shutdown

[Argannor]

Description

Adjusted the Start and Shutdown sequence of the prometheusexporter to prevent a race condition causing the close tcp 127.0.0.1:8999: use of closed network connection error as observed in #36139.

The behaviour was changed in the following ways:

• If an error occurs during the creation of the server, close the listener immediately, leaving shutdown a noop
• Since srv.Shutdown will close all open listeners, the explicit call to ln.Close in the shutdown routine was removed

Link to tracking issue

Fixes #36139

Testing

Unit testing, I temporarily increased the number of iterations on TestPrometheusExporter to 2000. The error did no longer occur. However sporadically another error occured:

=== RUN   TestPrometheusExporter
    prometheus_test.go:103: 
        	Error Trace:	C:/development/code/opentelemetry-collector-contrib/exporter/prometheusexporter/prometheus_test.go:84
        	Error:      	Received unexpected error:
        	            	listen tcp 127.0.0.1:8999: bind: Only one usage of each socket address (protocol/network address/port) is normally permitted.
        	Test:       	TestPrometheusExporter
--- FAIL: TestPrometheusExporter (1.16s)

I assume that this is because the OS (in my case Windows) won't always close the underlying sockets immediately, blocking it for some time afterwards. I'm not sure there is anything we can do about that.

Documentation

n/a

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: Argannor / name: Argannor (83a5851, 872c91e)