run with -O0 unless on release or backport branch

.buildkite/runtests.yml

@@ -1,49 +1,27 @@
----
 steps:
-  # Linux x86_64
-  - label: ":linux: linux-x86_64"
+  - label: "Tests"
     plugins:
-      # Julia installation outside the sandbox
-      - JuliaCI/julia#v1:
-          version: '1.10'
-      - staticfloat/sandbox#v2:
-          rootfs_url: https://github.com/JuliaCI/rootfs-images/releases/download/v6.00/package_linux.x86_64.tar.gz
-          rootfs_treehash: "4dcde853eb5baaa0a8f087b633eaf955dc94b5dc"
-          uid: 1000
-          gid: 1000
-      # Julia installation inside the sandbox
       - JuliaCI/julia#v1:
           version: "nightly"
     command: |
+      # Set optimization level based on branch name
+      if [[ "${BUILDKITE_BRANCH}" =~ ^backports-release-.*$ || "${BUILDKITE_BRANCH}" =~ ^release-.*$ ]]; then
+        OPT_LEVEL=2
+      else
+        OPT_LEVEL=0
+      fi
+
+      # Common Julia commands
       julia --color=yes --project=.ci -e 'using Pkg; Pkg.instantiate()'
-      julia --color=yes --project=.ci .ci/create_sysimage_and_run_tests.jl
+      julia --color=yes --project=.ci .ci/create_sysimage_and_run_tests.jl --optimize=$OPT_LEVEL
     agents:
       queue: "julia"
-      os: "linux"
-      arch: "x86_64"
-      cpuset_limited: "true"
     timeout_in_minutes: 120
-  # macOS aarch64
-  - label: ":macos: macos-aarch64"
-    plugins:
-      - JuliaCI/julia#v1:
-          version: "nightly"
-    command: |
-      julia --color=yes --project=.ci -e 'using Pkg; Pkg.instantiate()'
-      julia --color=yes --project=.ci .ci/create_sysimage_and_run_tests.jl
-    agents:
-      queue: "julia"
-      os: "macos"
-      arch: "aarch64"
-  # windows x86_64
-  - label: ":windows: windows-x86_64"
-    plugins:
-      - JuliaCI/julia#v1:
-          version: "nightly"
-    command: |
-      julia --color=yes --project=.ci -e 'using Pkg; Pkg.instantiate()'
-      julia --color=yes --project=.ci .ci/create_sysimage_and_run_tests.jl
-    agents:
-      queue: "julia"
-      os: "windows"
-      arch: "x86_64"
+    matrix:
+      # Define combinations of operating systems and architectures
+      - os: "linux"
+        arch: "x86_64"
+      - os: "macos"
+        arch: "aarch64"
+      - os: "windows"
+        arch: "x86_64"