LSAN detected errors have been fixed by a prior pathch (#3326), but
there are still some ASAN detected errors.
This patch try to fix these errors to make Doris BE more robustness.
And then we can add CI run in LSAN/ASAN mode to detect memory errors
as early as possible.
Note that the methods in path_util are only related to path processing,
and do not involve any file and IO operations
The upcoming patch will use these util methods, used to extract operations
such as concatenation of directory strings from processing logic.
