[v1.9.x] Remove the "copyright by contributors" line in source files (#20493)

* Remove Copyright contributor lines in the src directory

* Remove Copyright contributor lines in the include directory

* Add back lines removed by accident

* Remove empty comment line(s)

* Remove one extra * in the a comment line

* Remove the Copyright by Contributors line in tools directory

* Remove the Copyright by Contributors line in 3rdparty/mshadow directory

* Correct license header removed by accedent

Co-authored-by: Triston Cao <tristonc@nvidia.com>

Author: TristonC

3rdparty/mshadow/mshadow-ps/mshadow_ps.h

@@ -18,7 +18,6 @@
  */
 
 /*!
- *  Copyright (c) 2014 by Contributors
  * \file mshadow_ps.h
  * \brief parameter server abstraction for mshadow tensor
  *  this is a plugin of mshadow that can be used to syncrhonize

3rdparty/mshadow/mshadow-ps/ps_dist-inl.h

@@ -18,7 +18,6 @@
  */
 
 /*!
- *  Copyright (c) 2014 by Contributors
  * \file ps_dist-inl.h
  * \brief distributed version of PS
  *

3rdparty/mshadow/mshadow-ps/ps_local-inl.h

@@ -18,7 +18,6 @@
  */
 
 /*!
- *  Copyright (c) 2014 by Contributors
  * \file ps_local-inl.h
  * \brief local multi-threading implementation of PS abstraction
  *

3rdparty/mshadow/mshadow-ps/ps_rabit-inl.h

@@ -18,7 +18,6 @@
  */
 
 /*!
- *  Copyright (c) 2014 by Contributors
  * \file ps_rabit-inl.h
  * \brief distributed version of PS using BSP
  *     synchronization in the backend

3rdparty/mshadow/mshadow-ps/thread.h

@@ -18,7 +18,6 @@
  */
 
 /*!
- * Copyright by Contributors
  * \file thread.h
  * \brief this header include the minimum necessary resource
  * for multi-threading that can be compiled in windows, linux, mac

3rdparty/mshadow/mshadow-ps/thread_util.h

@@ -18,7 +18,6 @@
  */
 
 /*!
- * Copyright by Contributors
  * \file thread_util.h
  * \brief data structures for multi-threading communication
  * \author Tianqi Chen

3rdparty/mshadow/mshadow/base.h

@@ -18,7 +18,6 @@
  */
 
 /*!
- *  Copyright (c) 2014 by Contributors
  * \file base.h
  * \brief definitions of base types, operators, macros functions
  *

3rdparty/mshadow/mshadow/bfloat.h

@@ -18,7 +18,6 @@
  */
 
 /*!
- *  Copyright (c) 2019 by Contributors
  * \file bfloat.h
  * \brief definition of bfloat type.
  *

3rdparty/mshadow/mshadow/cuda/reduce.cuh

@@ -18,7 +18,6 @@
  */
 
 /*!
- *  Copyright (c) 2014 by Contributors
  * \file reduce.cuh
  * \brief helper functions to do reduction
  * \author Tianqi Chen

3rdparty/mshadow/mshadow/cuda/tensor_gpu-inl.cuh

@@ -18,7 +18,6 @@
  */
 
 /*!
- *  Copyright (c) 2014 by Contributors
  * \file tensor_gpu-inl.cuh
  * \brief implementation of GPU code using CUDA
  * \author Bing Xu, Tianqi Chen