editoast: move train schedule base to schemas #4939

Job	Run time
check_commits	7s
check_generated_railjson_sync	24s
build	20m 19s
check_railjson_generator	1m 43s
check_infra_schema_sync	21s
check_integration_tests	1m 25s
check_osrd_schema	46s
check_toml	8s
Check final newline	9s
check_editoast_lints	4m 36s
check_core	3m 43s
check_editoast_tests	4m 25s
check_front_rtk_sync	1m 37s
check_editoast_openapi	1m 22s
check_front	1m 52s
check_gateway	1m 23s
integration_tests	4m 32s
	48m 52s

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