Refactor the config for log dir of FE and BE
TLDR:
- Use env variable `LOG_DIR` to set root log dir
- Remove `sys_log_dir` for FE and BE
Details:
1. FE
1. The root log dir is set by env variable `LOG_DIR` in `fe.conf`
2. The default value of `audit_log_dir` is same as `${LOG_DIR}/`
3. The default value of `spark_launcher_log_dir` is `${LOG_DIR}/spark_launcher_log`
4. The default value of `nereids_trace_log_dir` is `${LOG_DIR}/nereids_trace_log`
5. The origin `sys_log_dir` is deprecated, and default value is `""`.
But for compatibility, if user already set `sys_log_dir` before, Doris will still use it as root log dir.
2. BE
1. The root log dir is set by env variable `LOG_DIR` in `be.conf`
2. Remove `pipeline_tracing_log_dir`, use `${LOG_DIR}` directly.
3. The origin `sys_log_dir` is deprecated, and default value is `""`.
But for compatibility, if user already set `sys_log_dir` before, Doris will still use it as root log dir.
38c5030f97