Simplify logic in boundedMemoryQueue, use channels len/cap #15412

Job	Run time
setup-environment	13s
govulncheck	34s
test-coverage	3m 46s
lint	4m 33s
cross-build-collector (darwin, amd64)	40s
checks	2m 43s
cross-build-collector (darwin, arm64)	58s
cross-build-collector (linux, 386)	40s
unittest-matrix (~1.21.4)	1m 43s
cross-build-collector (linux, amd64)	41s
unittest-matrix (~1.20.11)	1m 27s
cross-build-collector (linux, arm64)	1m 10s
cross-build-collector (linux, ppc64le)	44s
cross-build-collector (linux, arm, 7)	59s
cross-build-collector (linux, s390x)	45s
cross-build-collector (windows, 386)	1m 6s
cross-build-collector (windows, amd64)	44s
unittest	7s
	23m 33s

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