CI - csharp-testsuite v8 dance done properly

.github/workflows/ci.yml

@@ -702,6 +702,20 @@ jobs:
           save-if: false
           prefix-key: v1
 
+      # This step shouldn't be needed, but somehow we end up with caches that are missing librusty_v8.a.
+      # ChatGPT suspects that this could be due to different build invocations using the same target dir,
+      # and this makes sense to me because we only see it in this job where we mix `cargo build -p` with
+      # `cargo build --manifest-path` (which apparently build different dependency trees).
+      # However, we've been unable to fix it so... /shrug
+      - name: Check v8 outputs
+        run: |
+          find "${CARGO_TARGET_DIR}"/ -type f | grep '[/_]v8' || true
+          if ! [ -f "${CARGO_TARGET_DIR}"/release/gn_out/obj/librusty_v8.a ]; then
+            echo "Could not find v8 output file librusty_v8.a; rebuilding manually."
+            cargo clean --release -p v8 || true
+            cargo build --release -p v8
+          fi
+
       - name: Install SpacetimeDB CLI from the local checkout
         run: |
           cargo install --force --path crates/cli --locked --message-format=short
@@ -832,10 +846,10 @@ jobs:
       - name: Check v8 outputs
         run: |
           find "${CARGO_TARGET_DIR}"/ -type f | grep '[/_]v8' || true
-          if ! [ -f "${CARGO_TARGET_DIR}"/debug/gn_out/obj/librusty_v8.a ]; then
+          if ! [ -f "${CARGO_TARGET_DIR}"/release/gn_out/obj/librusty_v8.a ]; then
             echo "Could not find v8 output file librusty_v8.a; rebuilding manually."
-            cargo clean -p v8 || true
-            cargo build -p v8
+            cargo clean --release -p v8 || true
+            cargo build --release -p v8
           fi
 
       - name: Install SpacetimeDB CLI from the local checkout