Switch from the chrono `clock` feature to `now` #4296

Job	Run time
msrv	4m 23s
lint	3m 40s
external-types (opentelemetry)	1m 4s
external-types (opentelemetry-sdk)	1m 15s
non-default-examples (opentelemetry-otlp/examples/basic-otlp)	38s
test (stable)	7m 44s
test (beta)	6m 45s
cargo-deny	26s
coverage	3m 25s
docs	1m 28s
	30m 48s

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