fix: revert increasing size of MEM_MNGT_MB5_NB_BLOCKS

This commit reverts the change coming from
675fd0af.

On a test machine, running the basic simulator (both eNB, UE
and T tracer) with 100 RBs eats too much of memory on a computer
with 8GB of RAM, leading to a reboot because the computer
was not responsive anymore.

Other solutions are needed to solve the memory issues, but
multiplying by 50 this number is not a good one, at least
not in the basic mode of operation. If this value needs
to be that big, a #ifdef #else #endif may be used.

openair2/UTIL/MEM/mem_block.h

@@ -91,7 +91,7 @@ private_mem_block(void        check_free_mem_block (mem_block_t * leP);)
 
 #    define MEM_MNGT_MB5_BLOCK_SIZE     MEM_MNGT_MB0_BLOCK_SIZE*32
 // 2048
-#    define MEM_MNGT_MB5_NB_BLOCKS      1024 * MEM_SCALE * 50 // LG WAS 1024
+#    define MEM_MNGT_MB5_NB_BLOCKS      1024 * MEM_SCALE // LG WAS 1024
 #    define MEM_MNGT_POOL_ID5           5
 
 #    define MEM_MNGT_MB6_BLOCK_SIZE     MEM_MNGT_MB0_BLOCK_SIZE*64