refactor: replace substr with slice and remove dead code in singleContainer.ts #4048

Job	Run time
OCI Implementation Registry Compatibility	1m 23s
CLI	40s
Install Script (ubuntu-latest)	28s
Install Script (macos-latest)	26s
Tests Matrix (src/test/cli.exec.nonBuildKit.1.test.ts)	5m 35s
Tests Matrix (src/test/container-features/containerFeaturesOrder.test.ts)	47s
Tests Matrix (src/test/cli.exec.buildKit.1.test.ts)	5m 42s
Tests Matrix (src/test/cli.up.test.ts)	5m 47s
Tests Matrix (src/test/cli.exec.buildKit.2.test.ts)	5m 34s
Tests Matrix (src/test/container-features/containerFeaturesOCIPush.test.ts)	1m 11s
Tests Matrix (src/test/container-features/e2e.test.ts)	4m 13s
Tests Matrix (--exclude src/test/container-features/containerFeaturesOrder.test.ts --exclude src/...	7m 13s
Tests Matrix (src/test/cli.build.test.ts)	10m 16s
Tests Matrix (src/test/cli.exec.nonBuildKit.2.test.ts)	5m 11s
Tests Matrix (src/test/cli.test.ts)	1m 19s
Tests Matrix (src/test/cli.podman.test.ts)	2m 51s
Tests Matrix (src/test/container-features/featuresCLICommands.test.ts)	3m 8s
Tests Matrix (src/test/imageMetadata.test.ts)	6m 32s
Tests	-1s
	1h 8m 15s

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