fix: Remove datafusion-proto crate

We're not using if for anything yet, and this release seems to break building
container images.

```
error: builder for '/nix/store/75lddm4kg8mzn2x5nz8lg36gdj16p7ka-glaredb-cli-0.1.0.drv' failed with exit code 101;
       last 10 log lines:
       > Caused by:
       >   process didn't exit successfully: `/build/source/target/release/build/datafusion-proto-497b9ae0fe438eda/build-script-build` (exit status: 1)
       >   --- stdout
       >   cargo:rerun-if-env-changed=FORCE_REBUILD
       >   cargo:rerun-if-changed=proto/datafusion.proto
       >   Running: "/nix/store/2qg94y58v1jr4dw360bmpxlrs30m31ca-protobuf-3.19.4/bin/protoc" "--include_imports" "--include_source_info" "-o" "/build/prost-buildFXFfZG/prost-descriptor-set" "-I" "proto" "-I" "/nix/store/2qg94y58v1jr4dw360bmpxlrs30m31ca-protobuf-3.19.4/include" "proto/datafusion.proto"
       >
       >   --- stderr
       >   Error: "protobuf compilation failed: Permission denied (os error 13)"
       > warning: build failed, waiting for other jobs to finish...
       For full logs, run 'nix log /nix/store/75lddm4kg8mzn2x5nz8lg36gdj16p7ka-glaredb-cli-0.1.0.drv'.
```

Possibly related: apache/datafusion#3538

crates/arrowstore/Cargo.toml

@@ -17,7 +17,6 @@ tonic = { version = "0.8.0", features = ["transport", "codegen"] }
 prost = "0.11.0"
 futures = "0.3"
 datafusion = "12.0.0"
-datafusion-proto = "12.0.0"
 serde = { version = "1.0", features = ["derive", "rc"] }
 serde_json = "1.0"