Fix $files partition column construction

[tbaeg]

Description

During partition column construction, the referenced field(s) were not in the correct order which could cause IllegalArgumentException.

The FilesTablePageSource was updated to use field id look ups instead of relying solely on order.

java.lang.IllegalArgumentException: Wrong class, expected java.lang.CharSequence, but was java.lang.Boolean, for object: true
        at org.apache.iceberg.PartitionData.get(PartitionData.java:126)
        at io.trino.plugin.iceberg.system.files.FilesTablePageSource.lambda$getNextSourcePage$2(FilesTablePageSource.java:211)
        at io.trino.spi.block.RowBlockBuilder.buildEntry(RowBlockBuilder.java:111)
        at io.trino.plugin.iceberg.system.files.FilesTablePageSource.getNextSourcePage(FilesTablePageSource.java:204)
        at io.trino.operator.TableScanOperator.getOutput(TableScanOperator.java:262)
        at io.trino.operator.Driver.processInternal(Driver.java:403)
        at io.trino.operator.Driver.lambda$process$0(Driver.java:306)
        at io.trino.operator.Driver.tryWithLock(Driver.java:709)
        at io.trino.operator.Driver.process(Driver.java:298)
        at io.trino.operator.Driver.processForDuration(Driver.java:269)
        at io.trino.execution.SqlTaskExecution$DriverSplitRunner.processFor(SqlTaskExecution.java:851)
        at io.trino.execution.executor.dedicated.SplitProcessor.run(SplitProcessor.java:77)
        at io.trino.execution.executor.dedicated.TaskEntry$VersionEmbedderBridge.lambda$run$0(TaskEntry.java:205)
        at io.trino.$gen.Trino_477_4_g3fee187____20250925_141258_2.run(Unknown Source)
        at io.trino.execution.executor.dedicated.TaskEntry$VersionEmbedderBridge.run(TaskEntry.java:206)
        at io.trino.execution.executor.scheduler.FairScheduler.runTask(FairScheduler.java:177)
        at io.trino.execution.executor.scheduler.FairScheduler.lambda$submit$0(FairScheduler.java:164)
        at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:545)
        at com.google.common.util.concurrent.TrustedListenableFutureTask$TrustedFutureInterruptibleTask.runInterruptibly(TrustedListenableFutureTask.java:128)
        at com.google.common.util.concurrent.InterruptibleTask.run(InterruptibleTask.java:74)
        at com.google.common.util.concurrent.TrustedListenableFutureTask.run(TrustedListenableFutureTask.java:80)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1095)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:619)
        at java.base/java.lang.Thread.run(Thread.java:1447)

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

[raunaqmorarka]

Is this a regression from recent changes, or was it broken before as well ?

[tbaeg]

Is this a regression from recent changes, or was it broken before as well ?

I think it has always been an issue since the logic wasn't changed much from the previous implementation. When I get a chance I can verify.

[tbaeg]

Ran the same test on 476, and it passed; looks like it is a regression.

[tbaeg]

@ebyhr @chenjian2664 Gentle reminder.