chore: Use cached target directory (#2742)

#2596, in copying over the build steps from `publish`, added a `cargo clean` step which deletes the target dir that we cache in a prior step. Build times have suffered since, especially wrt the built assets. This restores the cached build artifacts.

.github/workflows/e2e.yml

@@ -49,7 +49,7 @@ jobs:
             ~/.cargo/registry
             ~/.cargo/git
             target
-          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}-${{ matrix.rust }}-1
+          key: ${{ matrix.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}-${{ matrix.rust }}-1
       - name: Install Rust toolchain
         uses: actions-rs/toolchain@v1
         with:
@@ -59,7 +59,6 @@ jobs:
         if: contains(matrix.os, 'macos')
       - name: Build
         run: |
-          cargo clean --target ${{ matrix.target }} --release
           cargo build --target ${{ matrix.target }} --locked --release
       - name: Strip binaries
         run: |