[SPARK-46293][CONNECT][PYTHON] Use protobuf transitive dependency

### What changes were proposed in this pull request?

This PR proposes to remove `protobuf` from required package.

### Why are the changes needed?

`protobuf` is automatically installed when installing `grpcio` and `grpcio-status`, so we don't need to specify the specific version explicitly.

### Does this PR introduce _any_ user-facing change?

No API changes.

### How was this patch tested?

The existing CI should pass

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes apache#44221 from itholic/protobuf_docs.

Authored-by: Haejoon Lee <haejoon.lee@databricks.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>

dev/requirements.txt

@@ -53,7 +53,6 @@ py
 # Spark Connect (required)
 grpcio>=1.59.3
 grpcio-status>=1.59.3
-protobuf==4.25.1
 googleapis-common-protos>=1.56.4
 
 # Spark Connect python proto generation plugin (optional)