Contribution analytics - design/frontend corrections

The contribution analytics is getting redesigned (issue: gitlab-org/gitlab-ee#6089 MR: gitlab-org/gitlab-ee!6194) but we had to skip a few things because of technical restraints. We need to address these things in this issue:

• Reduce spacing between chart and title + description (the chart is too far away from the title/description)
• Fix the gradients (they look too heavy and not evenly distributed)
• name slanting caused the first name to be cut off so we disabled it. We need to find a way to bring it back but make the first name readable.

plus: do we need the chevron to indicate that the chart can be scrolled?

The spacing is too large

Gradient looks too heavy

First name cut off when slanting is enabled

/cc @jeremy_