fix(workflow): remove macOS x86_64 platform from allocator benchmark jobs

fix(script): add rust and cargo installation to Alpine benchmark script

.github/scripts/allocator_bench_alpine.sh

@@ -8,7 +8,7 @@ fi
 
 ALPINE_SCRIPT=$(cat <<'EOF'
 set -eu
-apk add --no-cache build-base pkgconfig time
+apk add --no-cache build-base pkgconfig time rust cargo
 
 build_features() {
   allocator="$1"

.github/workflows/allocator-bench.yml

@@ -19,7 +19,6 @@ jobs:
           - ubuntu-24.04-arm-2
           - windows-2025
           - windows-11-arm
-          - macos-15-x86_64
           - macos-15-arm64
           - alpine-dockerized
         include:
@@ -39,10 +38,6 @@ jobs:
             platform_name: windows-11-arm
             runner: windows-11-arm
             alpine: false
-          - platform: macos-15-x86_64
-            platform_name: macos-15 x86_64
-            runner: macos-15-large
-            alpine: false
           - platform: macos-15-arm64
             platform_name: macos-15 arm64
             runner: macos-15