use all-features devshell for clippy/all in CI

Without this, we're building a static rocksdb inside the rust-rocksdb
build script every time. As far as I know this doesn't change clippy's
behavior, but it does take a *long* time.

engage.toml

@@ -68,13 +68,15 @@ script = "cargo clippy --workspace --all-targets --color=always -- -D warnings"
 name = "cargo-clippy/all"
 group = "lints"
 script = """
-cargo clippy \
-    --workspace \
-    --all-targets \
-    --all-features \
-    --color=always \
-    -- \
-    -D warnings
+env DIRENV_DEVSHELL=all-features \
+    direnv exec . \
+    cargo clippy \
+        --workspace \
+        --all-targets \
+        --all-features \
+        --color=always \
+        -- \
+        -D warnings
 """
 
 [[task]]