message: Add mb_config for Linux64 Release (reclient) builder
  Cr-Commit-Position: refs/heads/main@{#37898}
diff: 'Linux64 Release': 'release_bot_x64',
  'Linux64 Release (ARM)': 'release_bot_arm64',
  'Linux64 Release (Libfuzzer)': 'libfuzzer_asan_release_bot_x64',
  + 'Linux64 Release (reclient)': 'release_bot_x64_reclient',
  # Mac
  'Mac Asan': 'mac_asan_clang_release_bot_x64',
  'release_bot_arm': ['openh264', 'release_bot', 'arm'],
  'release_bot_arm64': ['openh264', 'release_bot', 'arm64'],
  'release_bot_x64': ['openh264', 'release_bot', 'x64'],
  + 'release_bot_x64_reclient': [
  + 'openh264', 'release_bot_reclient', 'x64',
  + ],
  'release_bot_x86': ['openh264', 'release_bot', 'x86'],
  'rtti_no_sctp_android_arm': [
  'android', 'debug_static_bot', 'arm', 'rtti', 'no_sctp'
  'pure_release_bot': {
  'mixins': ['release', 'goma', 'dcheck_off'],
  },
  + 'pure_release_bot_reclient': {
  + 'mixins': ['release', 'reclient', 'dcheck_off'],
  + },
  + 'reclient': {
  + 'gn_args': 'use_remoteexec=true',
  + },
  'release': {
  'gn_args': 'is_debug=false',
  },
  'release_bot': {
  'mixins': ['pure_release_bot', 'dcheck_always_on'],
  },
  + 'release_bot_reclient': {
  + 'mixins': ['pure_release_bot_reclient', 'dcheck_always_on'],
  + },
  'rtti': {
  'gn_args': 'use_rtti=true',
  },
  