avoid ly_tzset_once in ly_time_time2str

It does not seem necessary to call ly_tzset_once() from
ly_time_time2str().
If the user changes TZ env variable, they must explicitly call tzset()
as well.

Author: irfanHaslanded

src/tree_data_common.c

@@ -1791,9 +1791,6 @@ ly_time_time2str(time_t time, const char *fractions_s, char **str)
 
     LY_CHECK_ARG_RET(NULL, str, LY_EINVAL);
 
-    /* init timezone */
-    ly_tzset_once();
-
     /* convert */
     if (!localtime_r(&time, &tm)) {
         return LY_ESYS;