Save json logs to file when -ddump-json is combiled with -ddump-to-file (#22959)

Previously, when -ddump-json was used with -ddump-to-file, the logs were expected to be saved into files as described in the documentation (optionally specified with a filename prefix), but they were printed out to stdout regardless. Now, the JSON log action checks if log_dump_to_file is on, and if so, it redirects the log outputs to the corresponding log files in the same way as other dump files.