Clean-up: config: fix -Wshadow error in config_load_session

Clean-up: config: fix -Wshadow error in config_load_session

Fix:

      CC       libconfig_la-session-config.lo
    /home/simark/src/lttng-tools/src/common/config/session-config.c: In function ‘config_load_session’:
    /home/simark/src/lttng-tools/src/common/config/session-config.c:4020:9: error: declaration of ‘path’ shadows a parameter [-Werror=shadow]
     4020 |    char path[PATH_MAX];
          |         ^~~~
    /home/simark/src/lttng-tools/src/common/config/session-config.c:3999:37: note: shadowed declaration is here
     3999 | int config_load_session(const char *path, const char *session_name,
          |                         ~~~~~~~~~~~~^~~~

Change-Id: Id7d5f6fcf0e88f43dee420dfb174d9bf01aa8fbd
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>