Merge bitcoin/bitcoin#23219: p2p, refactor: tidy up LookupSubNet()

c44c20108f p2p, refactor: drop unused DNSLookupFn param in LookupSubnet() (Vasil Dimov)
f0c9e68080 p2p, refactor: tidy up LookupSubNet() (Jon Atack)

Pull request description:

  This pull originally resolved a code `TO-DO`, as well as fixing different param names between the function declaration and definition, updating the function to current style standards, clearer variable naming, and improving the Doxygen documentation.

  Following the merge of #17160, it now does the non-`TODO` changes and also now drops an unused param to simplify the function.

ACKs for top commit:
  dunxen:
    ACK c44c201
  vasild:
    ACK c44c20108f
  shaavan:
    crACK c44c20108f

Tree-SHA512: 55f64c7f403819dec84f4da06e63db50f7c0601a2d9a1ec196fda667c220ec6f5ad2a3c95e0e02275da9f6da6b984275d1dc10e19ed82005c5e13da5c5ecab02

src/test/fuzz/netbase_dns_lookup.cpp

@@ -64,7 +64,7 @@ FUZZ_TARGET(netbase_dns_lookup)
     }
     {
         CSubNet resolved_subnet;
-        if (LookupSubNet(name, resolved_subnet, fuzzed_dns_lookup_function)) {
+        if (LookupSubNet(name, resolved_subnet)) {
             assert(resolved_subnet.IsValid());
         }
     }