Fix flaky TableClientTest.testTableAPIServerSideRouting

[void-ptr974]

Motivation

TableClientTest.testTableAPIServerSideRouting can fail intermittently with txnResult.isSuccess() returning false.

Observed failure:

• CI job: https://github.com/apache/bookkeeper/actions/runs/26486972755/job/77997366483?pr=4741
• Test failure: java.lang.AssertionError at TableClientTest.java:257
• Bookie log context: RoutingHeaderProxyInterceptor failed while parsing the proxied TxnRequest for streamId=1026, rangeId=1030, and routing key txn-key.

Failed to intercept table request {rangeId=1030, routingKey=74786e2d6b6579, streamId=1026}
java.lang.IllegalArgumentException: Invalid unknonwn tag type: 4
    at org.apache.bookkeeper.stream.proto.kv.rpc.LightProtoCodec.skipUnknownField(...)
    at org.apache.bookkeeper.stream.proto.kv.rpc.TxnRequest.parseFrom(...)
    at org.apache.bookkeeper.stream.storage.impl.routing.RoutingHeaderProxyInterceptor.parseTxnRequest(...)

The server-side routing proxy forwards table requests as InputStreams. When the interceptor tries to rewrite the routing header, it reads the request stream first. If parsing or interception fails, the old fallback returned the same InputStream instance. At that point the stream has already been consumed, so the backend receives an empty or partially consumed request instead of the original request body. That can make the proxied txn fail and surfaces as the flaky integration test failure.

Changes

• Buffer the original request bytes before attempting to parse and rewrite proxied table requests.
• Reuse the buffered bytes when mutating the routing header for proxy-style InputStream requests.
• On interception failure, rebuild a fresh request stream from the original bytes so fallback forwarding preserves the request body.
• Add a regression test that sends invalid proxy request bytes through IdentityInputStreamMarshaller and verifies the delegate receives a fresh stream with the original payload.

Testing

• mvn -pl stream/storage/impl -am -P '!mac,!cargo-zigbuild' -DstreamTests -Dtest=RoutingHeaderProxyInterceptorTest -Dsurefire.failIfNoSpecifiedTests=false test