apacheGH-38198: [Go] Fix AuthenticateBasicToken to be reliable behind…

… proxies (apache#38199)

### Rationale for this change

Fixes a bug in the Go Flight client library that makes using AuthenticateBasicToken unreliable behind proxies.

### What changes are included in this PR?

Closes the sending side of the bi-directional stream for the Flight Handshake RPC call before trying to read the headers. This matches the C++ implementation.

<img width="609" alt="Screenshot 2023-10-11 at 6 18 40 PM" src="https://github.com/apache/arrow/assets/879445/05e23c6a-0ff8-41fc-825b-8add7fe938bc">

### Are these changes tested?

I've tested these changes against my service deployed behind CloudFlare and verified the error listed in the linked issue disappears.

### Are there any user-facing changes?

No
* Closes: apache#38198

Authored-by: Phillip LeBlanc <[email protected]>
Signed-off-by: Matt Topol <[email protected]>

go/arrow/flight/client.go

@@ -312,18 +312,18 @@ func (c *client) AuthenticateBasicToken(ctx context.Context, username, password
 		return ctx, err
 	}
 
-	header, err := stream.Header()
+	err = stream.CloseSend()
 	if err != nil {
 		return ctx, err
 	}
 
-	_, err = stream.Recv()
-	if err != nil && err != io.EOF {
+	header, err := stream.Header()
+	if err != nil {
 		return ctx, err
 	}
 
-	err = stream.CloseSend()
-	if err != nil {
+	_, err = stream.Recv()
+	if err != nil && err != io.EOF {
 		return ctx, err
 	}