fix(ci): add intra-cache-key cleanup, switch tests to debug mode

Two root causes from pipeline 2480888929:

1. /cache volume bloat — kurditv hit 93G/96G (97% full). The before_script
   pruned old cache KEYS but never cleaned other job dirs within the SAME key.
   Old test-partition-1/, test-partition-2/, wasm-check/, … accumulated across
   pipelines alongside the new test-release/ dir, filling the volume.
   Fix: add a second find that removes every sibling dir in CACHE_KEY/ except
   the current job's dir. .test-base keeps only test-release/; wasm-check keeps
   only wasm-check/. Each pipeline run starts with a clean slate per job type.

2. Release builds exceeded 300m — vps3 was still compiling
   pezbridge-hub-zagros-runtime at minute 300 in --release mode.
   Clippy (debug) took 162m cold; release mode is 2-3x slower.
   Fix: remove --release from all cargo nextest run commands. RUSTFLAGS already
   includes -Cdebug-assertions=y so assertion coverage is identical. Debug
   artifacts are smaller (less disk pressure) and compile faster.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitlab-ci.yml

@@ -375,11 +375,17 @@ cargo-audit:
     # cargo fingerprinting handles different feature sets within the same dir.
     - export CARGO_TARGET_DIR="/cache/cargo-target/${CACHE_KEY}/test-release"
     - mkdir -p "$CARGO_TARGET_DIR"
+    # Remove dirs with outdated cache keys (e.g. old Cargo.lock)
     - find /cache/cargo-target -mindepth 1 -maxdepth 1 -type d ! -name "${CACHE_KEY}" -exec rm -rf {} + 2>/dev/null || true
+    # Remove other job dirs within the SAME cache key — keeps only test-release.
+    # Previous per-job dirs (test-partition-1, test-no-try-runtime-2, …) accumulate
+    # and fill the /cache volume. One shared dir is all we need.
+    - find /cache/cargo-target/"${CACHE_KEY}" -mindepth 1 -maxdepth 1 -type d ! -name "test-release" -exec rm -rf {} + 2>/dev/null || true
     - echo "CARGO_TARGET_DIR=$CARGO_TARGET_DIR (disk $(df -h /cache/cargo-target | tail -1 | awk '{print $3 "/" $2 " used, " $4 " free"}'))"
   cache: []
-  # 300m: cold release build on VPS (jemalloc+rocksdb C compilation) can take 3h+.
-  # Warm cache (second run on same runner) completes in ~30m.
+  # 300m: cold debug build on VPS can still take 2-3h (first run after cache change).
+  # Warm cache completes in ~45m. Debug mode compiles 2-3x faster than --release
+  # while -Cdebug-assertions=y (set in RUSTFLAGS) keeps the same assertion coverage.
   timeout: 300m
   retry:
     max: 1
@@ -398,7 +404,7 @@ test-partition-1:
     - git config --global --add safe.directory '*'
     - |
       cargo nextest run \
-        --workspace --locked --release --no-fail-fast --cargo-quiet \
+        --workspace --locked --no-fail-fast --cargo-quiet \
         --features try-runtime,experimental,ci-only-tests \
         --partition count:1/3
   artifacts:
@@ -414,7 +420,7 @@ test-partition-2:
     - git config --global --add safe.directory '*'
     - |
       cargo nextest run \
-        --workspace --locked --release --no-fail-fast --cargo-quiet \
+        --workspace --locked --no-fail-fast --cargo-quiet \
         --features try-runtime,experimental,ci-only-tests \
         --partition count:2/3
   artifacts:
@@ -430,7 +436,7 @@ test-partition-3:
     - git config --global --add safe.directory '*'
     - |
       cargo nextest run \
-        --workspace --locked --release --no-fail-fast --cargo-quiet \
+        --workspace --locked --no-fail-fast --cargo-quiet \
         --features try-runtime,experimental,ci-only-tests \
         --partition count:3/3
     # First partition also runs runtime-api tests
@@ -448,7 +454,7 @@ test-no-try-runtime-1:
     - git config --global --add safe.directory '*'
     - |
       cargo nextest run \
-        --workspace --locked --release --no-fail-fast --cargo-quiet \
+        --workspace --locked --no-fail-fast --cargo-quiet \
         --features experimental,ci-only-tests \
         --partition count:1/2
 
@@ -458,7 +464,7 @@ test-no-try-runtime-2:
     - git config --global --add safe.directory '*'
     - |
       cargo nextest run \
-        --workspace --locked --release --no-fail-fast --cargo-quiet \
+        --workspace --locked --no-fail-fast --cargo-quiet \
         --features experimental,ci-only-tests \
         --partition count:2/2
 
@@ -476,7 +482,9 @@ wasm-check:
     - export CARGO_TARGET_DIR="/cache/cargo-target/${CACHE_KEY}/${CI_JOB_NAME}"
     - mkdir -p "$CARGO_TARGET_DIR"
     - find /cache/cargo-target -mindepth 1 -maxdepth 1 -type d ! -name "${CACHE_KEY}" -exec rm -rf {} + 2>/dev/null || true
-    - echo "CARGO_TARGET_DIR=$CARGO_TARGET_DIR"
+    # Keep only wasm-check dir; remove test-release and any other stale dirs
+    - find /cache/cargo-target/"${CACHE_KEY}" -mindepth 1 -maxdepth 1 -type d ! -name "${CI_JOB_NAME}" -exec rm -rf {} + 2>/dev/null || true
+    - echo "CARGO_TARGET_DIR=$CARGO_TARGET_DIR (disk $(df -h /cache/cargo-target | tail -1 | awk '{print $3 "/" $2 " used, " $4 " free"}'))"
   cache: []
   timeout: 2h
   retry: