Undo integration and MIRI changes

Author: alamb

.github/workflows/rust.yml

@@ -169,10 +169,10 @@ jobs:
       - uses: actions/checkout@v2
         with:
           submodules: true
-      - name: Setup Rust toolchain
-        uses: ./.github/actions/setup-builder
-        with:
-          rust-version: stable
+      - name: Setup toolchain
+        run: |
+          rustup toolchain install stable
+          rustup default stable
       - uses: actions/setup-python@v2
         with:
           python-version: "3.10"
@@ -372,12 +372,10 @@ jobs:
             target
           key: ${{ runner.os }}-cargo-miri-${{ hashFiles('**/Cargo.lock') }}
       - name: Setup Rust toolchain
-        uses: ./.github/actions/setup-builder
-        with:
-          rust-version: ${{ matrix.rust }}
-      - name: Install MIRI
         run: |
-          rustup component add miri
+          rustup toolchain install ${{ matrix.rust }}
+          rustup default ${{ matrix.rust }}
+          rustup component add rustfmt clippy miri
       - name: Run Miri Checks
         env:
           RUST_BACKTRACE: full