Migrating angles to chevrons on Escalation Policy page

What does this MR do and why?

Fixes #362788 (closed), migrating the angle to a chevron.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Navigate to Monitor > On-Call Schedules
2. Create an On-Call Schedule
3. Navigate to Monitor > Escalation Policy
4. Create an Escalation Policy
5. Chevrons are next to the displayed escalation policy name

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.