[ews-app] Use passwords.json instead of environment variables. Similar to https://bugs.webkit.org/show_bug.cgi?id=263009 and https://bugs.webkit.org/show_bug.cgi?id=261907
<rdar://problem/117155033>
Pull request: https://github.com/WebKit/WebKit/pull/19520
Committed 269772@main (81dce146552a): <https://commits.webkit.org/269772@main> Reviewed commits have been landed. Closing PR #19520 and removing active labels.
Deployed this on ews-app production instance.