[tests] Increase timeout for TestGRPCResolverRoundRobin

[yurishkuro]

Resolves #2025.

At first this was just adding extra logging, but per the next comment the logging indicated that it's indeed a timing issue.

Also did some clean-up of the code, like pre-allocating arrays with the right sizes.

[yurishkuro]

ha, interesting, the logging already yielded fruit, the test failed like this:

    grpc_resolver_test.go:100: 
        	Error Trace:	grpc_resolver_test.go:100
        	            				grpc_resolver_test.go:156
        	Error:      	Should be true
        	Test:       	TestGRPCResolverRoundRobin/minPeers=3
        	Messages:   	Connection #0 was still not up. Connections so far: map[]

Because it's the very first connection that failed, it can only be due to timing, as there are no other conditions. Also, first connections in the subsequent tests are often acquired after 2-3 hundred iterations, almost half of the total time, e.g. this one at 400:

=== RUN   TestGRPCResolverRoundRobin/minPeers=7
    grpc_resolver_test.go:95: connected to peer #0 (127.0.0.1:40041) on iteration 440
    grpc_resolver_test.go:95: connected to peer #1 (127.0.0.1:44157) on iteration 1
    grpc_resolver_test.go:95: connected to peer #2 (127.0.0.1:41503) on iteration 0
    grpc_resolver_test.go:95: connected to peer #3 (127.0.0.1:38727) on iteration 1
    grpc_resolver_test.go:95: connected to peer #4 (127.0.0.1:32919) on iteration 0

Even though we have a pretty long timeout already (1000 * 10ms = 10s), I am going to increase it even more.

[codecov]

Codecov Report

Merging #2729 (dface2f) into master (2f8ffa9) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2729      +/-   ##
==========================================
+ Coverage   95.73%   95.75%   +0.01%     
==========================================
  Files         216      217       +1     
  Lines        9599     9619      +20     
==========================================
+ Hits         9190     9211      +21     
  Misses        336      336              
+ Partials       73       72       -1     

Impacted Files	Coverage Δ
cmd/agent/app/reporter/connect_metrics.go	100.00% <100.00%> (ø)
cmd/agent/app/reporter/grpc/builder.go	95.83% <100.00%> (+0.83%)	⬆️
cmd/agent/app/reporter/grpc/collector_proxy.go	100.00% <100.00%> (ø)
pkg/discovery/grpcresolver/grpc_resolver.go	100.00% <100.00%> (ø)
plugin/storage/integration/integration.go	77.34% <0.00%> (-0.56%)	⬇️
cmd/query/app/static_handler.go	96.52% <0.00%> (+1.73%)	⬆️

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[yurishkuro]

this is the main change/fix