[keyserver][web] Refactor getInitialReduxState action

Summary: issue: https://linear.app/comm/issue/ENG-5181/refactor-getinitialreduxstate-action

Test Plan: Checked that the value returned by this action is correct, chekced that the app loads without errors

Reviewers: michal, kamil, ginsu

Reviewed By: michal

Subscribers: ashoat, tomek, wyilio

Differential Revision: https://phab.comm.dev/D9650