[refactor] Update GetAddr_() function signature

Update so the internal function signature matches the external one, as is the
case for the other addrman functions.

src/addrman.cpp

@@ -745,7 +745,7 @@ std::pair<CAddress, int64_t> AddrManImpl::Select_(bool newOnly) const
     }
 }
 
-void AddrManImpl::GetAddr_(std::vector<CAddress>& vAddr, size_t max_addresses, size_t max_pct, std::optional<Network> network) const
+std::vector<CAddress> AddrManImpl::GetAddr_(size_t max_addresses, size_t max_pct, std::optional<Network> network) const
 {
     AssertLockHeld(cs);
 
@@ -759,8 +759,9 @@ void AddrManImpl::GetAddr_(std::vector<CAddress>& vAddr, size_t max_addresses, s
 
     // gather a list of random nodes, skipping those of low quality
     const int64_t now{GetAdjustedTime()};
+    std::vector<CAddress> addresses;
     for (unsigned int n = 0; n < vRandom.size(); n++) {
-        if (vAddr.size() >= nNodes)
+        if (addresses.size() >= nNodes)
             break;
 
         int nRndPos = insecure_rand.randrange(vRandom.size() - n) + n;
@@ -776,8 +777,10 @@ void AddrManImpl::GetAddr_(std::vector<CAddress>& vAddr, size_t max_addresses, s
         // Filter for quality
         if (ai.IsTerrible(now)) continue;
 
-        vAddr.push_back(ai);
+        addresses.push_back(ai);
     }
+
+    return addresses;
 }
 
 void AddrManImpl::Connected_(const CService& addr, int64_t nTime)
@@ -1080,10 +1083,9 @@ std::vector<CAddress> AddrManImpl::GetAddr(size_t max_addresses, size_t max_pct,
 {
     LOCK(cs);
     Check();
-    std::vector<CAddress> vAddr;
-    GetAddr_(vAddr, max_addresses, max_pct, network);
+    const auto addresses = GetAddr_(max_addresses, max_pct, network);
     Check();
-    return vAddr;
+    return addresses;
 }
 
 void AddrManImpl::Connected(const CService &addr, int64_t nTime)

src/addrman_impl.h

@@ -242,12 +242,13 @@ private:
     /**
      * Return all or many randomly selected addresses, optionally by network.
      *
-     * @param[out] vAddr         Vector of randomly selected addresses from vRandom.
      * @param[in] max_addresses  Maximum number of addresses to return (0 = all).
      * @param[in] max_pct        Maximum percentage of addresses to return (0 = all).
      * @param[in] network        Select only addresses of this network (nullopt = all).
+     *
+     * @returns                  A vector of randomly selected addresses from vRandom.
      */
-    void GetAddr_(std::vector<CAddress>& vAddr, size_t max_addresses, size_t max_pct, std::optional<Network> network) const EXCLUSIVE_LOCKS_REQUIRED(cs);
+    std::vector<CAddress> GetAddr_(size_t max_addresses, size_t max_pct, std::optional<Network> network) const EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     /** We have successfully connected to this peer. Calling this function
      *  updates the CAddress's nTime, which is used in our IsTerrible()