chore: upgrade Rust toolchain to 1.94.0 (#6460)

Upgrades the pinned Rust toolchain from 1.91.0 to 1.94.0.

The only code change needed was boxing two futures in
`build_partial_fixture` in the `distributed_vector_build` bench, where
1.94's stricter layout computation overflowed the default recursion
limit. Boxing makes the awaited futures' sizes constant (a pointer),
breaking the recursion.

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: wjones127

java/lance-jni/src/session.rs

@@ -11,7 +11,6 @@ use lance::session::Session as LanceSession;
 use lance_io::object_store::ObjectStoreRegistry;
 
 use crate::error::{Error, Result};
-use crate::ok_or_throw_with_return;
 
 /// Creates a new Session and returns a handle to it.
 ///

rust-toolchain.toml

@@ -1,5 +1,5 @@
 # We keep this pinned to keep clippy and rustfmt in sync between local and CI.
 # Feel free to upgrade to bring in new lints.
 [toolchain]
-channel = "1.91.0"
+channel = "1.94.0"
 components = ["rustfmt", "clippy", "rust-analyzer"]

rust/lance/benches/distributed_vector_build.rs

@@ -281,7 +281,8 @@ async fn build_partial_fixture(dataset: &mut Dataset, bench_case: BenchCase) ->
     }
 
     let fragment_groups = contiguous_fragment_groups(dataset, bench_case.num_shards);
-    let (ivf_params, pq_params) = train_shared_ivf_pq(dataset, bench_case.num_partitions).await;
+    let (ivf_params, pq_params) =
+        Box::pin(train_shared_ivf_pq(dataset, bench_case.num_partitions)).await;
     let params = VectorIndexParams::with_ivf_pq_params(DistanceType::L2, ivf_params, pq_params);
 
     for fragments in fragment_groups {
@@ -290,7 +291,7 @@ async fn build_partial_fixture(dataset: &mut Dataset, bench_case: BenchCase) ->
             .name("distributed_merge_only".to_string())
             .fragments(fragments)
             .index_uuid(fixture_uuid.to_string());
-        builder.execute_uncommitted().await.unwrap();
+        Box::pin(builder.execute_uncommitted()).await.unwrap();
     }
 
     MergeFixture {

rust/lance/src/dataset/write.rs

@@ -428,7 +428,7 @@ impl WriteParams {
 /// IDs can be assigned after writing is complete.
 #[deprecated(
     since = "0.20.0",
-    note = "Use [`InsertBuilder::write_uncommitted_stream`] instead"
+    note = "Use [`InsertBuilder::execute_uncommitted_stream`] instead"
 )]
 pub async fn write_fragments(
     dest: impl Into<WriteDestination<'_>>,