acct_gather_profile/influxdb - Fix 3 memory leaks related to tables struct.

==6281== 36 bytes in 2 blocks are definitely lost in loss record 123 of 292
==6281==    at 0x4C2FB45: calloc
(in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==6281==    by 0x502B72F: slurm_xmalloc (xmalloc.c:84)
==6281==    by 0x502CA2A: xstrdup (xstring.c:350)
==6281==    by 0x7F9552C: ???
==6281==    by 0x4F3419D: acct_gather_profile_g_create_dataset
(slurm_acct_gather_profile.c:648)
...
==6281== 160 bytes in 2 blocks are definitely lost in loss record 234 of 292
==6281==    at 0x4C2FD4F: realloc
(in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==6281==    by 0x502B8AB: slurm_xrealloc (xmalloc.c:143)
==6281==    by 0x7F955C8: ???
==6281==    by 0x4F3419D: acct_gather_profile_g_create_dataset
(slurm_acct_gather_profile.c:648)
...
==6281== 552 (160 direct, 392 indirect) bytes in 2 blocks are definitely
lost in loss record 257 of 292
==6281==    at 0x4C2FD4F: realloc
(in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==6281==    by 0x502B8AB: slurm_xrealloc (xmalloc.c:143)
==6281==    by 0x7F95581: ???
==6281==    by 0x4F3419D: acct_gather_profile_g_create_dataset
(slurm_acct_gather_profile.c:648)

Bug 2693.