REST Client not sending headers when using InputStream

[dominikrebhan]

Describe the bug

With Quarkus 3.8.3 the REST Client won't send any headers when the input is an InputStream. I think this is related to #39265

Expected behavior

Send input headers as before or when using no InputStreama as input.

Actual behavior

No headers are sent.

How to Reproduce?

`private final Client client = ClientBuilder.newClient();

@GET
@Path("bytes")
@Produces(MediaType.TEXT_PLAIN)
public int testWithBytes() throws Exception {
    var response = client.target("http://192.168.2.172:9090")
            .path("/")
            .request()
            .header("X-Test", "FOO")
            .post(Entity.entity("Hello World".getBytes(StandardCharsets.UTF_8),
                    "text/plain"));

    return response.getStatus();
}

@GET
@Path("stream")
@Produces(MediaType.TEXT_PLAIN)
public int testWithStream() throws Exception {
    var response = client.target("http://192.168.2.172:9090")
            .path("/")
            .request()
            .header("X-Test", "FOO")
            .post(Entity.entity(new ByteArrayInputStream("Hello World".getBytes(StandardCharsets.UTF_8)),
                    "text/plain"));

    return response.getStatus();
}`

Output of uname -a or ver

No response

Output of java -version

No response

Quarkus version or git rev

3.8.3

Build tool (ie. output of mvnw --version or gradlew --version)

No response

Additional information

No response

[quarkus-bot]

/cc @cescoffier (rest-client), @geoand (rest-client)

[geoand]

This has already been fixed in main and will be available with the next 3.8 release