[improve] API job_progress shouldn't returns the data field of job progress

[wyxxxcat]

issue : #263

before

{"success":true,"job_progress":"{\"job_name\":\"test\",\"sync_state\":501,\"sub_sync_state\":{\"state\":-1,\"binlog_type\":-1},\"job_sync_id\":1732704080,\"prev_commit_seq\":7033,\"commit_seq\":7033,\"table_mapping\":null,\"table_commit_seq_map\":null,\"data\":\"{\\\"commit_seq\\\":7033,\\\"txn_id\\\":2007,\\\"dest_table_ids\\\":[63037],\\\"table_records\\\":[{\\\"_\\\":63025,\\\"partitionRecords\\\":[{\\\"partitionId\\\":63024,\\\"range\\\":\\\"\\\",\\\"version\\\":4,\\\"isTempPartition\\\":false,\\\"stid\\\":-1}],\\\"indexIds\\\":[63026]}],\\\"commit_infos\\\":[{\\\"tabletId\\\":63040,\\\"backendId\\\":10005},{\\\"tabletId\\\":63042,\\\"backendId\\\":10005},{\\\"tabletId\\\":63044,\\\"backendId\\\":10005}],\\\"is_txn_insert\\\":false,\\\"source_stid\\\":null,\\\"desc_stid\\\":null,\\\"sub_txn_infos\\\":null}\",\"created_at\":1732704079,\"full_sync_start_at\":1732704079,\"incremental_sync_start_at\":1732704121,\"ingest_binlog_at\":1732704181}"}

now

{"success":true,"job_progress":{"job_name":"test","sync_state":501,"sub_sync_state":{"state":-1,"binlog_type":-1},"job_sync_id":1732704080,"prev_commit_seq":7033,"commit_seq":7033,"table_mapping":null,"table_commit_seq_map":null,"data":"","created_at":1732704079,"full_sync_start_at":1732704079,"incremental_sync_start_at":1732704121,"ingest_binlog_at":1732704181}}