refactor: reduced new objects when parsing SpdxLicense #363

Job	Run time
e2e (3.13.0, test/commands/test/async_main/async_main_test.dart)	1m 30s
e2e (3.13.0, test/commands/test/compilation_error/compilation_error_test.dart)	1m 37s
e2e (3.13.0, test/commands/test/no_project/no_project_test.dart)	1m 22s
e2e (3.13.0, test/commands/test/spaced_golden_file_name/spaced_golden_file_name_test.dart)	1m 50s
e2e (3.13.0, test/commands/create/flutter_app/core_test.dart)	2m 11s
e2e (3.13.0, test/commands/create/dart_cli/dart_cli_test.dart)	1m 55s
e2e (3.13.0, test/commands/create/dart_package/dart_pkg_test.dart)	1m 37s
e2e (3.13.0, test/commands/create/docs_site/docs_site_test.dart)	2m 24s
e2e (3.13.0, test/commands/create/flutter_package/flutter_pkg_test.dart)	1m 56s
e2e (3.13.0, test/commands/create/flutter_plugin/flutter_plugin_test.dart)	5m 22s
e2e (any, test/commands/test/async_main/async_main_test.dart)	1m 30s
e2e (any, test/commands/test/compilation_error/compilation_error_test.dart)	1m 25s
e2e (any, test/commands/test/no_project/no_project_test.dart)	1m 23s
e2e (any, test/commands/test/spaced_golden_file_name/spaced_golden_file_name_test.dart)	2m 6s
e2e (any, test/commands/create/flutter_app/core_test.dart)	2m 9s
e2e (any, test/commands/create/dart_cli/dart_cli_test.dart)	2m 33s
e2e (any, test/commands/create/dart_package/dart_pkg_test.dart)	2m 5s
e2e (any, test/commands/create/docs_site/docs_site_test.dart)	2m 54s
e2e (any, test/commands/create/flutter_package/flutter_pkg_test.dart)	1m 51s
e2e (any, test/commands/create/flutter_plugin/flutter_plugin_test.dart)	6m 28s
	46m 8s

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