Remove memcheck.

Since the linux_memcheck trybot is no more, this CL removes all the
code needed to make it work.

Bug: webrtc:7737, webrtc:8356, webrtc:9570
Change-Id: I09a9467b8bf895146a3384c2c915b54662721af6
Reviewed-on: https://webrtc-review.googlesource.com/90863
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Reviewed-by: Oleh Prypin <oprypin@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24201}
diff --git a/tools_webrtc/mb/mb.py b/tools_webrtc/mb/mb.py
index 43b44cb..7f196bb 100755
--- a/tools_webrtc/mb/mb.py
+++ b/tools_webrtc/mb/mb.py
@@ -857,20 +857,7 @@
       else:
         cmdline.append('../../testing/test_env.py')
 
-      # Memcheck is only supported for linux. Ignore in other platforms.
-      if is_linux and 'rtc_use_memcheck=true' in vals['gn_args']:
-        cmdline += [
-            'bash',
-            '../../tools_webrtc/valgrind/webrtc_tests.sh',
-            '--tool',
-            'memcheck',
-            '--target',
-            'Release',
-            '--build-dir',
-            '..',
-            '--test',
-        ]
-      elif test_type != 'raw':
+      if test_type != 'raw':
         extra_files += [
             '../../third_party/gtest-parallel/gtest-parallel',
             '../../third_party/gtest-parallel/gtest_parallel.py',