[Stream][Binlog] Override scan-state comparison for OlapStreamScan

[yujun777]

Description

While reviewing PR #65472, I found that LogicalOlapTableStreamScan has stream-specific state that is relevant to scan equivalence, especially StreamReadMode (INCREMENTAL, SNAPSHOT, and RESET). The class includes readMode in equals(), but it does not provide a stream-specific hasSameScanState() override.

After PR #65472 makes scan-state comparison relevant to plan rewrites such as PullUpJoinFromUnionAll, two stream scans may be compared through the generic OLAP scan-state logic without explicitly checking stream-specific state. If scans with different stream read modes are treated as equivalent, a rewrite could reuse or merge a scan with different stream semantics.

Requested follow-up

Please add an override for hasSameScanState() in LogicalOlapTableStreamScan (or the corresponding OlapStreamScan abstraction) and include all stream-specific state that affects execution. Add FE unit tests covering:

• equal stream scans with the same read mode;
• different read modes;
• any selected-partition or stream-lowering state that must participate in scan equivalence.

This is a source-level follow-up to PR #65472. The direct stream/binlog runtime impact still needs an end-to-end reproduction; this issue is opened to ensure the missing override and its contract are resolved explicitly.

上面这个PR 会先pick 到4.1 分支，但是4.1分支现在不支持stream， 所以要等后面4.1支持了stream之后， 再单独pick stream scan的overrite 到4.1 分支上

Related tracking issues:

• #65265
• #65418