Use shorter strings in the macOS matrix configuration

By having the full names of runner and native it meant in many
places GitHub displayed ... instead of the full matrix entry.

Therefore, use a simpler arch matrix and derive the runner/native
values from it.

Author: jonahgraham

.github/workflows/maven.yml

@@ -123,17 +123,11 @@ jobs:
       fail-fast: false
       matrix:
         java: ['21']
-        native: [cocoa.macosx.x86_64, cocoa.macosx.aarch64]
-        runner: [macos-15-intel, macos-latest]
-        exclude:
-          - runner: macos-latest
-            native: cocoa.macosx.x86_64
-          - runner: macos-15-intel
-            native: cocoa.macosx.aarch64
+        arch: [x86_64, aarch64]
     uses: ./.github/workflows/build.yml
     with:
-      runner: ${{ matrix.runner }}
+      runner: ${{ matrix.arch == 'x86_64' && 'macos-15-intel' || 'macos-latest' }}
       java: ${{ matrix.java }}
-      native: ${{ matrix.native }}
+      native: ${{ matrix.arch == 'x86_64' && 'cocoa.macosx.x86_64' || 'cocoa.macosx.aarch64' }}
       performance: ${{ contains(github.event.pull_request.labels.*.name, 'performance') }}
       runtodotests: ${{ contains(github.event.pull_request.labels.*.name, 'runtodotests') }}