fix: properly end goroutine in benchmark

[vladopajic]

PR Description

For loop used in the benchmark to discard messages was not properly terminated.

for {
	<-mbx.ReceiveC()
}
// <---- this is unreachable code

This loop will keep iterating because result from ReceiveC() was never checked.

Change in second for loop is more of cosmetic purposes, I hope you don't mind that.

Which issue(s) this PR fixes

Notes to the Reviewer

PR Checklist

• CHANGELOG.md updated
• Documentation added
• Tests updated
• Config converters updated

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