fix: align bulk insert schema handling (#8222)

* fix: align bulk insert schema handling

Carry `aligned_schema_version` through bulk insert requests so datanode can recheck stale schemas only when needed. Use the physical data region schema version for metric logical bulk inserts, while external bulk insert callers leave alignment unknown.

Related files:
- `Cargo.toml`
- `Cargo.lock`
- `src/store-api/src/region_request.rs`
- `src/metric-engine/src/engine/bulk_insert.rs`
- `src/mito2/src/request.rs`
- `src/mito2/src/worker/handle_bulk_insert.rs`
- `src/mito2/src/worker/handle_write.rs`
- `src/operator/src/bulk_insert.rs`
- `src/servers/src/pending_rows_batcher.rs`
- `src/mito2/src/engine/edit_region_test.rs`

Signed-off-by: Lei, HUANG <mrsatangel@gmail.com>

* test: cover bulk insert missing columns

Add Flight bulk insert coverage for batches that omit nullable columns and verify the database fills the missing values with nulls.

Related files:
- `tests-integration/src/grpc/flight.rs`

Signed-off-by: Lei, HUANG <mrsatangel@gmail.com>

* chore: update proto to main branch commit

Signed-off-by: Lei, HUANG <mrsatangel@gmail.com>

* fix: align physical metric bulk insert schema

Pass the physical schema version through metric bulk insert requests so
physical and logical region writes share the same schema alignment behavior.

Files:
- \`src/metric-engine/src/engine/bulk_insert.rs\` — updates \`bulk_insert_physical_region\` and reuses \`physical_schema_version\` for bulk insert schema alignment.

Signed-off-by: Lei, HUANG <mrsatangel@gmail.com>

* chore: add some doc

Signed-off-by: Lei, HUANG <mrsatangel@gmail.com>

---------

Signed-off-by: Lei, HUANG <mrsatangel@gmail.com>

src/operator/src/bulk_insert.rs

@@ -106,6 +106,7 @@ impl Inserter {
                     region_id: region_id.as_u64(),
                     partition_expr_version: partition_expr_version
                         .map(|value| PartitionExprVersion { value }),
+                    aligned_schema_version: None,
                     body: Some(bulk_insert_request::Body::ArrowIpc(ArrowIpc {
                         schema: schema_bytes.clone(),
                         data_header: raw_flight_data.data_header,
@@ -220,6 +221,7 @@ impl Inserter {
                                 region_id: region_id.as_u64(),
                                 partition_expr_version: partition_expr_version
                                     .map(|value| PartitionExprVersion { value }),
+                                aligned_schema_version: None,
                                 body: Some(bulk_insert_request::Body::ArrowIpc(ArrowIpc {
                                     schema: schema_bytes,
                                     data_header: header,