Fix design inconsistencies in work items child/linked widget item metadata

What does this MR do and why?

This MR addresses some design inconsistencies in the Child/Linked widgets item metadata, notably:

• Makes all metadata items (icon & text) gray-500
• Removes some of the metadata specific styles, and instead applies them to the wrapper (gl-text-sm , gl-text-secondary)
• Adjusts the gap between metadata items to 8px
• Aligns all metadata items to use flex for icon/count, where some were using margin instead
• Removes some extra undesired spacing (weight metadata had an unnecessary min-width)

Note: there are some additional known spacing/alignment issues that are already being addressed separately

• Extra ul currently showing due to padding issue
• Padding issue due to Crud change

MR acceptance checklist

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Screenshots or screen recordings

Example	Before	After
Work Item Widgets
Legacy Widgets

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