Flink: Add RemoveDanglingDeleteFiles support to the Flink maintenance API

### Feature Request / Improvement

# Problem

The `RemoveDanglingDeleteFiles` interface is defined in `iceberg-api` but the only
implementation is `RemoveDanglingDeletesSparkAction` (Spark-only). Flink users have
no equivalent, which causes equality delete files to accumulate indefinitely in
tables managed by the Flink maintenance API.

### Root cause

`RewriteDataFiles` in the Flink maintenance pipeline does not remove dangling delete
files after compaction. There are two existing cleanup paths in the Spark
implementation:

**Path A — `ManifestFilterManager` (unreliable)**
During a `RewriteFiles` commit, `ManifestFilterManager` removes delete files whose
sequence number is less than the global minimum data file sequence number across the
entire table. In practice, this condition is rarely satisfied: data files that have
already reached the target size are never rewritten, keeping their original low
sequence numbers and permanently anchoring the global minimum below the eq-delete
sequence numbers.

**Path B — `remove-dangling-deletes=true` (Spark-only, #6126)**
`RewriteDataFilesSparkAction` offers a `remove-dangling-deletes` option that invokes
`RemoveDanglingDeletesSparkAction` after compaction. It correctly computes
`min(data_file.sequence_number)` per partition using a Spark DataFrame join on the
`ENTRIES` metadata table, then calls `table.newRewrite().deleteFile(danglingDelete).commit()`.
This is the correct fix for Path A's shortcomings.

The Flink maintenance API has neither path working reliably.

### Observed impact

In a partitioned V2 table written by `IcebergSink` (equality deletes):

- After multiple rounds of `RewriteDataFiles`, data files that have already reached
the target size are excluded from rewrite groups and retain their original low
sequence numbers.
- These files anchor the global `minDataSequenceNumber`, preventing Path A from
ever removing the eq-delete files.
- `removedEqualityDeleteFiles` is always `null` in every commit summary.
- Equality delete file count grows monotonically with each write, never decreasing.

The only workaround is to temporarily set `rewriteAll(true)`, which forces all data
files — including large ones — into rewrite groups, draining the global minimum and
allowing Path A to fire. This is wasteful and should not be the normal operating mode.

### Summary

Is there an existing mechanism in the Flink maintenance API that handles this case,
or would it make sense to add `RemoveDanglingDeleteFiles` support here?

### Query engine

Flink

### Willingness to contribute

- [ ] I can contribute this improvement/feature independently
- [x] I would be willing to contribute this improvement/feature with guidance from the Iceberg community
- [ ] I cannot contribute this improvement/feature at this time

Start with the Flink maintenance API's RewriteDataFiles pipeline and compare its cleanup behavior with RewriteDataFilesSparkAction and RemoveDanglingDeletesSparkAction. Trace how RemoveDanglingDeleteFiles is defined in iceberg-api and how the Spark action computes per-partition data-file sequence numbers. Done means Flink compaction removes dangling equality delete files without requiring rewriteAll(true), with coverage for the reported partitioned-table case.

Written by the indexing model from the issue text.