Revert "Make llvm::telemetry::Manager::preDispatch protected. (#127114)"

This reverts commit f7a2d70.

Multiple buildbot failures have been reported.  See:
#127114

Author: kazutakahirata

llvm/include/llvm/Telemetry/Telemetry.h

@@ -138,6 +138,10 @@ class Manager {
 public:
   virtual ~Manager() = default;
 
+  // Optional callback for subclasses to perform additional tasks before
+  // dispatching to Destinations.
+  virtual Error preDispatch(TelemetryInfo *Entry) = 0;
+
   // Dispatch Telemetry data to the Destination(s).
   // The argument is non-const because the Manager may add or remove
   // data from the entry.
@@ -146,11 +150,6 @@ class Manager {
   // Register a Destination.
   void addDestination(std::unique_ptr<Destination> Destination);
 
-protected:
-  // Optional callback for subclasses to perform additional tasks before
-  // dispatching to Destinations.
-  virtual Error preDispatch(TelemetryInfo *Entry) {}
-
 private:
   std::vector<std::unique_ptr<Destination>> Destinations;
 };

llvm/lib/Telemetry/Telemetry.cpp

@@ -1,16 +1,3 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-///
-/// \file
-/// This file provides the basic framework for Telemetry.
-/// Refer to its documentation at llvm/docs/Telemetry.rst for more details.
-//===---------------------------------------------------------------------===//
-
 #include "llvm/Telemetry/Telemetry.h"
 
 namespace llvm {