Exclusively use OAI_RNGSEED env variable everywhere

Hide normal table initialization of Ziggurat generator from outside to
force the usage of randominit() for RNG initialization. In this step,
remove the randominit() seed parameter and only rely on OAI_RNGSEED for
a consistent RNG initialization, as this parameter was used differently
("0" as fixed number or to force a random seed).

Now, only use OAI_RNGSEED env variable to force the usage of a fixed
seed.

executables/nr-uesoftmodem.c

@@ -340,7 +340,6 @@ int main(int argc, char **argv)
   T_Config_Init();
 #endif
   initTpool(get_softmodem_params()->threadPoolConfig, &(nrUE_params.Tpool), cpumeas(CPUMEAS_GETSTATE));
-  //randominit (0);
   set_taus_seed (0);
 
   if (!has_cap_sys_nice())