Add toString to IcebergOptimizeHandle, static import in IcebergMetadata

[homar]

Description

Small changes that are necessary to implement expire_snapshots and delete_orpahn_files for iceberg.

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Documentation

(.) No documentation is needed.
( ) Sufficient documentation is included in this PR.
( ) Documentation PR is available with #prnumber.
( ) Documentation issue #issuenumber is filed, and can be handled later.

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# Section
* Fix some things. ({issue}`issuenumber`)

[findepi]

generate the toString using Intellij, prefer Guava's toStringHelper (except in SPI where Guava is not on the pass, use StringJoiner there)

    @Override
    public String toString()
    {
        return toStringHelper(this)
                .add("schemaAsJson", schemaAsJson)
                .add("partitionSpecAsJson", partitionSpecAsJson)
                .add("tableColumns", tableColumns)
                .add("fileFormat", fileFormat)
                .add("tableStorageProperties", tableStorageProperties)
                .add("maxScannedFileSize", maxScannedFileSize)
                .add("retriesEnabled", retriesEnabled)
                .toString();
    }

[findepi]

in the meantime retriesEnabled was added to the class, add it to the toString too

[losipiuk]

nit: Code reformat -> Static import