Update bundle CTA UI.

[leilenah]

Reasons for making this change

Bundle CTAs are currently aligned at the bottom of the bundle content section. This creates a lot of space in between bundle content and bundle CTAs.

This change does a couple things:

1. Removes the space between bundle content and bundle CTAs
2. Updates bundle CTA UI to aesthetically align with the CTAs in the NewRun form

Related issues

#4189

Screenshots

Checklist

• I've added a screenshot of the changes, if this is a frontend change
• I've added and/or updated tests, if this is a backend change
• I've run the pre-commit.sh script
• I've updated docs, if needed

[percyliang]

Great, thanks!