sergey-safarov created an issue (kamailio/kamailio#4257)

### Description

We found a memory leak in the AVP cleanup

### Troubleshooting

#### Reproduction

To reproduce, you need to start Kaamilio 5.8 branch with the config ``` listen=127.0.0.1:5060

tcp_send_timeout=3

loadmodule "xlog.so" loadmodule "kex.so" loadmodule "pv.so" loadmodule "ctl.so" loadmodule "jsonrpcs.so" loadmodule "tm.so" loadmodule "siptrace.so"

modparam("siptrace", "trace_to_database", 0) modparam("siptrace", "trace_on", 1) modparam("siptrace", "trace_mode", 1) modparam("siptrace", "trace_init_mode", 1)

loadmodule "permissions.so" modparam("permissions", "address_file", "address.list") modparam("permissions", "peer_tag_avp", "$avp(s:tag)") modparam("permissions", "peer_tag_mode", 0) modparam("permissions", "load_backends", 1) modparam("permissions", "reload_delta", 1)

loadmodule "dispatcher.so" modparam("dispatcher", "list_file", "/tmp/dispatcher.list") modparam("dispatcher", "ds_ping_from", "sip:proxy@aggregator.nga911.com") modparam("dispatcher", "ds_ping_interval", 3) modparam("dispatcher", "ds_probing_mode", 1)

route{ drop; }

event_route[siptrace:msg] { if (allow_address("1", "$siptrace(src_hostip)", "0")) { xerr("SIP message from $siptrace(src_hostip)\n"); } } ``` Also need to create `address.list` with content ``` # address file - records to match with allow_address(...) and variants # * file format details # - comments start with # and go to end of line # - each line corresponds to a record with following attributes: # # (groupid,int) (address,str) (netmask,int,o), (port,int,o) (tag,str,o) # # * description of the tokens used to describe line format # - int: expected integer value # - str: expected string value # - o: optional field

1 127.0.0.0 16 0 tag ``` and `/tmp/dispatcher.list` with content ``` 1 sip:sip.telnyx.com:5060;transport=tcp 8 ```

When kamailio started required to execute a command ``` kamcmd mod.stats core shm| grep avp ``` This will produce output like ``` create_avp(178): 1360 init_avps(92): 16 init_avps(91): 16 ``` Where `create_avp` is constantly increasing