These flows are already classified as TLS.RDP.
This change also fix a memory leak
```
Direct leak of 62 byte(s) in 1 object(s) allocated from:
#0 0x5883d762429f in __interceptor_malloc /src/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:68:3
#1 0x5883d76fe46a in ndpi_malloc ndpi/src/lib/ndpi_memory.c:57:46
#2 0x5883d76fe46a in ndpi_strdup ndpi/src/lib/ndpi_memory.c:110:13
#3 0x5883d77adcd6 in ndpi_compute_ja4 ndpi/src/lib/protocols/tls.c:2298:46
#4 0x5883d77ab2ec in processClientServerHello ndpi/src/lib/protocols/tls.c:3314:10
#5 0x5883d77a4c51 in processTLSBlock ndpi/src/lib/protocols/tls.c:1319:5
```
Found by oss-fuzz.
See: https://oss-fuzz.com/testcase-detail/5244512192757760
There is some overlap between RTP and Raknet detection: give precedence
to RTP logic.
Consequences:
* Raknet might require a little bit more packets for some flows (not a
big issue)
* some very small (1-2 pkts) Raknet flows are not classified (not sure
what do do about that..)
