[license] Remove duplicated valgrind license file

LICENSE.valgrind is a stale copy of src/third_party/valgrind/LICENSE

Change-Id: I274ad8cbe4e347979a9152b3a31c4598d2525aa4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2398458Reviewed-by: Dan Elphick <delphick@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69873}

LICENSE.valgrind

-----------------------------------------------------------------
-
-Notice that the following BSD-style license applies to this one
-file (valgrind.h) only.  The rest of Valgrind is licensed under the
-terms of the GNU General Public License, version 2, unless
-otherwise indicated.  See the COPYING file in the source
-distribution for details.
-
-----------------------------------------------------------------
-
-This file is part of Valgrind, a dynamic binary instrumentation
-framework.
-
-Copyright (C) 2000-2007 Julian Seward.  All rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions
-are met:
-
-1. Redistributions of source code must retain the above copyright
-   notice, this list of conditions and the following disclaimer.
-
-2. The origin of this software must not be misrepresented; you must 
-   not claim that you wrote the original software.  If you use this 
-   software in a product, an acknowledgment in the product 
-   documentation would be appreciated but is not required.
-
-3. Altered source versions must be plainly marked as such, and must
-   not be misrepresented as being the original software.
-
-4. The name of the author may not be used to endorse or promote 
-   products derived from this software without specific prior written 
-   permission.
-
-THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
-OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
-WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
-ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
-DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
-DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
-GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
-INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
-WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
-NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
-SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.