[web] remove margin from search component

Summary:
In this diff I remove the margin in the Search component. In subsquent diffs there are some modals that use the Search component and now that we want the edges of the Search component to be flush with the padding of the modals we need to remove the margin in this component and introduce padding containers for the search bars that still need it

Depends on D10319

Test Plan: Confirmed that all places that needed a padding container around the search bar still looked the same

Reviewers: atul, rohan, kamil

Reviewed By: rohan

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D10320