Simplify analytics borders, padding and margins

Problem

The pages under analytics have been evolving each milestone, with new features and more UI elements being utilised. This has led to some possible duplication and also use of old / redundant css classes.

We have a lot of css classes to apply padding, margins and other general layout for value stream analytics, we should revisit the current classes that are used, in favour of utility classes where we can and or removing any redundant styling.

Background

The following discussion from !31069 (merged) and !38029 (merged) should be addressed:

• @ekigbo started a discussion:

  Outside the scope of this MR, but maybe in the near future it might be good to revisit the padding / margin classes we are using around content blocks. I suspect we could probably simplify them a little. Perhaps make use of some generic <box> components or something like that.

• Could our .gl-border-t-gray- etc classes be used here?

• Can we please use the gl prefixed classes here? It's out of scope for this MR but as we're already updating the template, we could update all the classes being used here

Page specific CSS

• cycle_analytics.scss
• ee/cycle_analytics.scss