Reduce allocs on first call to WithAttributes or WithLinks for new spans/events #13399

Job	Run time
lint	2m 59s
compatibility-test (~1.22.5, ubuntu-latest, 386)	39s
test-coverage	1m 19s
compatibility-test (~1.22.5, ubuntu-latest, amd64)	1m 8s
test-race	2m 9s
compatibility-test (~1.22.5, macos-latest, amd64)	50s
compatibility-test (~1.22.5, windows-latest, 386)	3m 25s
compatibility-test (~1.22.5, windows-latest, amd64)	3m 5s
compatibility-test (~1.22.5, actuated-arm64-2cpu-8gb, arm64)	1m 54s
compatibility-test (~1.21.12, ubuntu-latest, 386)	40s
compatibility-test (~1.21.12, ubuntu-latest, amd64)	1m 18s
compatibility-test (~1.21.12, macos-latest, amd64)	59s
compatibility-test (~1.21.12, windows-latest, 386)	2m 0s
test-bench	1m 4s
compatibility-test (~1.21.12, windows-latest, amd64)	3m 5s
compatibility-test (~1.21.12, actuated-arm64-2cpu-8gb, arm64)	1m 54s
codecov	5s
test-compatibility	1s
	28m 34s

Provide feedback