Support SD card readers appearing as USB mass storage

The mediacard_combo storage watcher was unable to detect SD card readers
that appear as SCSI/USB mass storage devices (/dev/sda) instead of
mmcblk devices. This caused insertion tests to timeout.

This patch enhances MediacardComboStorage._parse_journal_line() to:
- Detect insertions via 'detected capacity change from 0 to X' messages
- Detect removals via 'detected capacity change from X to 0' messages
- Extract partition names from 'sda: sda1' style journal entries
- Label these devices as 'SD/MMC via USB reader'

The fix allows the action state to be updated dynamically, properly
handling multiple insert/remove cycles even when a card is already
inserted at test start.

Tested with USB SD card readers that enumerate as /dev/sda devices.

Author: chochien

checkbox-support/checkbox_support/scripts/run_watcher.py

@@ -369,6 +369,30 @@ def _parse_journal_line(self, line_str):
         MediacardStorage._parse_journal_line(self, line_str)
         USBStorage._parse_journal_line(self, line_str)
 
+        # Also handle SD card readers that appear as SCSI/USB mass storage (sd*)
+        # Check for capacity change patterns first (for action detection)
+        if (
+            "detected capacity change from 0 to" in line_str
+            and " to 0" not in line_str
+        ):
+            # This is an insertion - always update to reflect current action
+            self.action = "insertion"
+            self.device = "SD/MMC via USB reader"
+        elif (
+            "detected capacity change from" in line_str and " to 0" in line_str
+        ):
+            # This is a removal - always update to reflect current action
+            self.action = "removal"
+
+        # Then extract partition name from patterns like "sda: sda1"
+        if not self.mounted_partition:
+            part_re = re.compile(r"sd\w+:.*(?P<part_name>sd\w+)")
+            match = re.search(part_re, line_str)
+            if match:
+                self.mounted_partition = match.group("part_name")
+
+        return super()._parse_journal_line(line_str)
+
 
 class ThunderboltStorage(StorageWatcher):
     """