Runner list: Fix alignment of items

What does this MR do and why?

Runner list: Fix alignment of items

• Changes the description to use the default font size the subtle design token
• Changes spacings to use gap
• Aligns spacings between rows
• Improves mobile layout
  • Alignment of table items to left
  • Changes Checkbox label to Select

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1. Go to https://gdk.test:3000/admin/runners

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Related to #512693 (closed)