[landing] remove derek and steven from team page

Summary: remove derek and steven from team page. @atul lmk if I should remove the picture files from AWS as well

Test Plan:
Please look at the screenshots to see the changes I made

Before:

After:

Reviewers: atul, tomek, ashoat

Reviewed By: ashoat

Subscribers: ashoat, tomek, atul

Differential Revision: https://phab.comm.dev/D6184