fix: skip filename-based split detection for media files in get_data_…

[Work4itnow]

Fixes #7201

Problem

When a user has an image file named train.png in a flat folder,
the library mistakenly treats it as a split name instead of an image,
resulting in only that one file being loaded.

Fix

Modified _get_data_files_patterns in data_files.py to skip
filename-based split detection when all matched files are media files
(images, audio, video). This causes it to fall through to
DEFAULT_PATTERNS_ALL which correctly loads all files.

Test

Added test_data_files_with_image_named_after_split to verify
that all images are loaded when one is named after a split.