Repaced and removed css gl-last-of-type-border-b-0

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This MR is removing global class gl-last-of-type-border-b-0 and replaced in places where it used to be and still need to be applied with gitlab tailwind class

Repaced and removed css gl-last-of-type-border-b-0

Removed:

• global css class
• file hooks list
• web hooks list

Changed:

• milestones list
• labels list

Changelog: changed

Additionally removed class !-gl-my-3 from file hooks list tag due to not centered content inside line wrapper

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Related to #482696 (closed)