Remove dead "send" additional CFG node and unused SendInstruction

Author: Copilot

go/ql/lib/semmle/go/controlflow/ControlFlowGraphShared.qll

@@ -574,11 +574,6 @@ module GoCfg {
           tag = "result-zero-init:" + i.toString()
         )
         or
-        // Send node
-        n instanceof Go::SendStmt and
-        not n = any(Go::CommClause cc).getComm() and
-        tag = "send"
-        or
         // Implicit deref
         implicitDerefCondition(n) and tag = "implicit-deref"
         or

go/ql/lib/semmle/go/controlflow/IR.qll

@@ -191,8 +191,6 @@ module IR {
       or
       this instanceof ReadResultInstruction and result = "result read"
       or
-      this instanceof SendInstruction and result = "send"
-      or
       this instanceof InitParameterInstruction and result = "parameter initialization"
       or
       this instanceof ReadArgumentInstruction and result = "argument"
@@ -1046,15 +1044,6 @@ module IR {
     override ControlFlow::Root getRoot() { var = result.(FuncDef).getAResultVar() }
   }
 
-  /** An instruction corresponding to a send statement. */
-  class SendInstruction extends Instruction {
-    SendStmt send;
-
-    SendInstruction() { this.isAdditional(send, "send") }
-
-    override ControlFlow::Root getRoot() { result.isRootOf(send) }
-  }
-
   /** An instruction initializing a parameter to the corresponding argument. */
   class InitParameterInstruction extends WriteInstruction {
     Parameter parm;