fix: always write devcontainer.metadata label as JSON array #4085

Job	Run time
OCI Implementation Registry Compatibility	1m 5s
Install Script (ubuntu-latest)	26s
CLI	39s
Install Script (macos-latest)	30s
Tests Matrix (src/test/cli.exec.buildKit.2.test.ts)	5m 21s
Tests Matrix (src/test/container-features/containerFeaturesOrder.test.ts)	50s
Tests Matrix (src/test/container-features/featuresCLICommands.test.ts)	2m 52s
Tests Matrix (src/test/container-features/e2e.test.ts)	3m 42s
Tests Matrix (src/test/cli.exec.nonBuildKit.2.test.ts)	4m 49s
Tests Matrix (src/test/cli.exec.nonBuildKit.1.test.ts)	4m 59s
Tests Matrix (src/test/imageMetadata.test.ts)	6m 9s
Tests Matrix (src/test/cli.test.ts)	1m 10s
Tests Matrix (--exclude src/test/container-features/containerFeaturesOrder.test.ts --exclude src/...	5m 49s
Tests Matrix (src/test/container-features/containerFeaturesOCIPush.test.ts)	57s
Tests Matrix (src/test/cli.exec.buildKit.1.test.ts)	5m 3s
Tests Matrix (src/test/cli.up.test.ts)	5m 39s
Tests Matrix (src/test/cli.podman.test.ts)	2m 26s
Tests Matrix (src/test/cli.build.test.ts)	9m 28s
Tests	4s
	1h 1m 58s

Provide feedback