Integrate benchmark building into existing build workflows

Instead of having separate workflow files for each platform's benchmarks,
integrate benchmark building as a new job in the existing build-reusable
workflow. This approach:
- Reduces workflow file duplication
- Reuses existing build caches for efficiency
- Makes benchmarks depend on successful main build
- Maintains benchmark builds across all platforms

Changes:
- Added build-benches job to build-reusable.yaml
- Removed 8 separate bench-*.yaml workflow files
- build-benches depends on build job and reuses its cache
- Updated CHANGELOG to reflect the integration approach

Author: dannywillems

.github/workflows/bench-macos-13.yaml

@@ -131,6 +131,33 @@ jobs:
       - name: Build tests
         run: make build-tests-webrtc
 
+  build-benches:
+    needs: [build]
+    timeout-minutes: 60
+    runs-on: ${{ inputs.os }}
+    env:
+      RUSTFLAGS: "-C overflow-checks=off -C debug-assertions=off ${{ inputs.rustflags }}"
+    steps:
+      - name: Git checkout
+        uses: actions/checkout@v5
+
+      - name: Setup build dependencies
+        uses: ./.github/actions/setup-build-deps
+
+      - name: Use shared OCaml setting up steps
+        uses: ./.github/actions/setup-ocaml
+        with:
+          ocaml_version: ${{ inputs.ocaml_version }}
+
+      - name: Setup Rust
+        uses: ./.github/actions/setup-rust
+        with:
+          toolchain: 1.84
+          cache-prefix: build-${{ inputs.os }}-${{ inputs.cache-prefix }}v0
+
+      - name: Build benchmarks
+        run: make build-benches
+
   build-wasm:
     if: ${{ inputs.build-wasm }}
     timeout-minutes: 60

.github/workflows/bench-macos-14.yaml

@@ -75,8 +75,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#1528](https://github.com/o1-labs/mina-rust/pull/1528/))
 - **Codebase**: remove unused `ledger/src/poseidon/fp.rs` file
   ([#1538](https://github.com/o1-labs/mina-rust/pull/1538))
-- **Ledger**: convert unused binary to proper criterion benchmarks with CI
-  support across all platforms
+- **Ledger**: convert unused binary to proper criterion benchmarks. Benchmarks
+  are now built as part of the existing build workflows across all platforms,
+  reusing build caches for efficiency
   ([#1539](https://github.com/o1-labs/mina-rust/pull/1539))
 
 ## v0.17.0