message: Prevent 8 cores bots to be used by desktop perf tests.
  Cr-Commit-Position: refs/heads/main@{#38761}
diff: @@ -2890,6 +2890,7 @@ buckets {
  name: "Perf Fuchsia"
  swarming_host: "chromium-swarm.appspot.com"
  swarming_tags: "vpython:native-python-wrapper"
  + dimensions: "cores:2"
  dimensions: "os:Linux"
  dimensions: "pool:luci.webrtc.perf"
  exe {
  @@ -2939,6 +2940,7 @@ buckets {
  name: "Perf Linux Bionic"
  swarming_host: "chromium-swarm.appspot.com"
  swarming_tags: "vpython:native-python-wrapper"
  + dimensions: "cores:2"
  dimensions: "os:Linux"
  dimensions: "pool:luci.webrtc.perf"
  exe {
  @@ -2988,6 +2990,7 @@ buckets {
  name: "Perf Mac 11"
  swarming_host: "chromium-swarm.appspot.com"
  swarming_tags: "vpython:native-python-wrapper"
  + dimensions: "cores:2"
  dimensions: "os:Linux"
  dimensions: "pool:luci.webrtc.perf"
  exe {
  @@ -3037,6 +3040,7 @@ buckets {
  name: "Perf Mac M1 Arm64 12"
  swarming_host: "chromium-swarm.appspot.com"
  swarming_tags: "vpython:native-python-wrapper"
  + dimensions: "cores:2"
  dimensions: "os:Linux"
  dimensions: "pool:luci.webrtc.perf"
  exe {
  @@ -3086,6 +3090,7 @@ buckets {
  name: "Perf Win7"
  swarming_host: "chromium-swarm.appspot.com"
  swarming_tags: "vpython:native-python-wrapper"
  + dimensions: "cores:2"
  dimensions: "os:Linux"
  dimensions: "pool:luci.webrtc.perf"
  exe {
  