fetch doesnt need target dirs

Dockerfile

@@ -90,13 +90,10 @@ COPY . .
 # TODO: clean needed because of rust upgrade and jenkins caches :'(
 RUN --mount=type=cache,target=/root/.cargo/git \
     --mount=type=cache,target=/root/.cargo/registry \
-    --mount=type=cache,target=/app/target \
-    --mount=type=cache,target=/app/target_test \
     set -eux -o pipefail; \
     \
     [ -e "$(pwd)/payment-contracts/src/contracts/mod.rs" ] || touch "$(pwd)/payment-contracts/build.rs"; \
-    cargo --locked fetch; \
-    CARGO_TARGET_DIR=target_test cargo --locked fetch
+    cargo --locked fetch
 
 # build tests (done its in own FROM so that it can run in parallel)
 FROM rust_with_env as build_tests