otelconf: Flaky test `Test_otlpGRPCTraceExporter`

[pellared]

Example run: https://github.com/open-telemetry/opentelemetry-go-contrib/actions/runs/15533686054/job/43727904638?pr=7445

go test -timeout 60s -short ./otelconf/...
go: downloading go.opentelemetry.io/otel/sdk v1.36.1-0.20250528182540-e25861aa7b3a
go: downloading go.opentelemetry.io/otel/sdk/log/logtest v0.0.0-20250521073539-a85ae98dcedc
?   	go.opentelemetry.io/contrib/otelconf	[no test files]
ok  	go.opentelemetry.io/contrib/otelconf/v0.2.0	0.169s
2025/06/09 11:49:34 reader is not registered
2025/06/09 11:49:34 reader is not registered
--- FAIL: Test_otlpGRPCTraceExporter (25.54s)
    --- FAIL: Test_otlpGRPCTraceExporter/with_TLS_config_and_client_key (10.81s)
        trace_test.go:968: 
            	Error Trace:	D:/a/opentelemetry-go-contrib/opentelemetry-go-contrib/otelconf/v0.3.0/trace_test.go:969
            	            				C:/hostedtoolcache/windows/go/1.23.0/x64/src/runtime/asm_386.s:1393
            	Error:      	Received unexpected error:
            	            	traces export: context deadline exceeded: rpc error: code = DeadlineExceeded desc = context deadline exceeded
        trace_test.go:968: 
            	Error Trace:	D:/a/opentelemetry-go-contrib/opentelemetry-go-contrib/otelconf/v0.3.0/trace_test.go:968
            	Error:      	Condition never satisfied
            	Test:       	Test_otlpGRPCTraceExporter/with_TLS_config_and_client_key
FAIL
FAIL	go.opentelemetry.io/contrib/otelconf/v0.3.0	31.766s

[pellared]

This looks to be introduced in:

• otelconf: add tests for grpc exporters with different certificate configurations #7233

@bacherfl, are you able to take a look at this issue?

[bacherfl]

@pellared I'm currently on sick leave but I will take a look as soon as I'm back at work if no one beat me to it by then

[bacherfl]

i'm back from sick leave now and will look into this today