[net processing] Change cs_main TRY_LOCK to LOCK in SendMessages()

This was changed to TRY_LOCK in #1117 to fix a potential deadlock
between cs_main and cs_vSend. cs_vSend was split into cs_vSend and
cs_sendProcessing in #9535 (and cs_sendProcessing was changed from a
TRY_LOCK to a LOCK in the same PR).

Since cs_vSend can no longer be taken before cs_main, revert this to a
LOCK().

This commit leaves part of the code with bad indentation. That is fixed
by the next (whitespace change only) commit.

Author: jnewbery

src/net_processing.cpp

@@ -3838,7 +3838,7 @@ class CompareInvMempoolOrder
 bool PeerLogicValidation::SendMessages(CNode* pto)
 {
     const Consensus::Params& consensusParams = Params().GetConsensus();
-    {
+
         // Don't send anything until the version handshake is complete
         if (!pto->fSuccessfullyConnected || pto->fDisconnect)
             return true;
@@ -3875,9 +3875,8 @@ bool PeerLogicValidation::SendMessages(CNode* pto)
             }
         }
 
-        TRY_LOCK(cs_main, lockMain);
-        if (!lockMain)
-            return true;
+    {
+        LOCK(cs_main);
 
         if (MaybeDiscourageAndDisconnect(*pto)) return true;
 
@@ -4416,7 +4415,7 @@ bool PeerLogicValidation::SendMessages(CNode* pto)
                 pto->m_tx_relay->nextSendTimeFeeFilter = timeNow + GetRandInt(MAX_FEEFILTER_CHANGE_DELAY) * 1000000;
             }
         }
-    }
+    } // release cs_main
     return true;
 }