Revert "[lldb] Fix error : unknown error while starting lldb's C/C++ repl (llvm#153560)"

This reverts commit 00ffd8b.

The change breaks lldb greendragon tests

Namely, TestClangREPL.py

Author: rastogishubham

lldb/source/Commands/CommandObjectExpression.cpp

@@ -640,15 +640,9 @@ void CommandObjectExpression::DoExecute(llvm::StringRef command,
             repl_sp->SetValueObjectDisplayOptions(m_varobj_options);
           }
 
-          if (!expr.empty()) {
-            result.GetOutputStream().Printf(
-                "Warning: trailing input is ignored in --repl mode\n");
-          }
-
           IOHandlerSP io_handler_sp(repl_sp->GetIOHandler());
           io_handler_sp->SetIsDone(false);
           debugger.RunIOHandlerAsync(io_handler_sp);
-          return;
         } else {
           repl_error = Status::FromErrorStringWithFormat(
               "Couldn't create a REPL for %s",

lldb/test/API/repl/clang/TestClangREPL.py

@@ -56,16 +56,6 @@ def test_basic_completion(self):
 
         self.quit()
 
-        # Re-enter the REPL with trailing input to trigger warning.
-        self.child.send("expression --repl -l c -- 3 + 3\n")
-        self.child.expect_exact("Warning: trailing input is ignored in --repl mode\n")
-        self.child.expect_exact("1>")
-
-        # Evaluate another expression after warning.
-        self.expect_repl("4 + 4", substrs=["(int) $3 = 8"])
-
-        self.quit()
-
     # PExpect uses many timeouts internally and doesn't play well
     # under ASAN on a loaded machine..
     @skipIfAsan