sdk/metric: Add experimental Enabled method to synchronous instruments #15152

Job	Run time
compatibility-test (1.23.0, ubuntu-latest, 386)	1m 8s
compatibility-test (1.23.0, ubuntu-latest, amd64)	37s
compatibility-test (1.23.0, otel-linux-arm64, arm64)	40s
compatibility-test (1.23.0, macos-13, amd64)	1m 37s
lint	2m 15s
compatibility-test (1.23.0, macos-latest, arm64)	40s
compatibility-test (1.23.0, windows-latest, 386)	1m 44s
compatibility-test (1.23.0, windows-latest, amd64)	3m 36s
test-bench	34s
compatibility-test (~1.22.5, ubuntu-latest, 386)	25s
compatibility-test (~1.22.5, ubuntu-latest, amd64)	1m 11s
test-concurrent-safe	3m 57s
compatibility-test (~1.22.5, otel-linux-arm64, arm64)	34s
test-coverage	42s
compatibility-test (~1.22.5, macos-13, amd64)	1m 16s
compatibility-test (~1.22.5, macos-latest, arm64)	58s
compatibility-test (~1.22.5, windows-latest, 386)	2m 29s
test-race	2m 3s
compatibility-test (~1.22.5, windows-latest, amd64)	1m 33s
codecov	5s
test-compatibility	1s
	28m 5s

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