Spark: Fix file_list_view prefix matching to exclude sibling paths in DeleteOrphanFiles

[maoli67660]

Problem

filteredCompareToFileList() in DeleteOrphanFilesSparkAction filters the caller-provided file_list_view dataset using:

files = files.filter(files.col(FILE_PATH).startsWith(location));

Because location has no trailing /, a sibling path that shares the table location as a raw string prefix is incorrectly included. For example, when the table is at s3://bucket/my_table, files under s3://bucket/my_table_backup/ also satisfy startsWith("s3://bucket/my_table") and get pulled into orphan detection for the wrong table.

Fixes #16493.

Solution

Append / to location before the prefix match:

String locationPrefix = location.endsWith("/") ? location : location + "/";
files = files.filter(files.col(FILE_PATH).startsWith(locationPrefix));

Applied to Spark 3.5, 4.0, and 4.1.

Testing

Added testRemoveOrphanFilesFileListViewDoesNotMatchSiblingPaths to TestRemoveOrphanFilesProcedure in all three Spark versions. The test:

1. Creates an empty Iceberg table at a known location
2. Builds a file_list_view that includes an orphan file inside the table directory and a file under a sibling path (table-location + "-sibling")
3. Runs remove_orphan_files with file_list_view and dry_run => true
4. Asserts the sibling file is not identified as an orphan, and the in-table orphan is identified

[maoli67660]

Closing this as a duplicate of #16498, which has been open since May and takes the same approach (and already uses LocationUtil.stripTrailingSlash(location) + PATH_SEPARATOR, which is cleaner than my conditional check). I'll help review #16498 instead to get the fix landed.