navbar: Drop unused classes from navbar template.
navbar: Drop unused classes from navbar template.

The class "searchbox-rightmargin" was only referenced in this file and
has hence been removed in this commit.

timabbott/zulip,hackerkid/zulip,hackerkid/zulip,zulip/zulip,shubhamdhama/zulip,timabbott/zulip,brainwane/zulip,kou/zulip,punchagan/zulip,hackerkid/zulip,andersk/zulip,rht/zulip,showell/zulip,kou/zulip,kou/zulip,shubhamdhama/zulip,punchagan/zulip,synicalsyntax/zulip,zulip/zulip,shubhamdhama/zulip,eeshangarg/zulip,synicalsyntax/zulip,hackerkid/zulip,rht/zulip,hackerkid/zulip,showell/zulip,showell/zulip,kou/zulip,punchagan/zulip,brainwane/zulip,brainwane/zulip,zulip/zulip,brainwane/zulip,timabbott/zulip,showell/zulip,andersk/zulip,punchagan/zulip,zulip/zulip,timabbott/zulip,punchagan/zulip,brainwane/zulip,timabbott/zulip,eeshangarg/zulip,andersk/zulip,andersk/zulip,rht/zulip,rht/zulip,shubhamdhama/zulip,punchagan/zulip,shubhamdhama/zulip,showell/zulip,hackerkid/zulip,rht/zulip,andersk/zulip,synicalsyntax/zulip,andersk/zulip,brainwane/zulip,zulip/zulip,zulip/zulip,eeshangarg/zulip,eeshangarg/zulip,shubhamdhama/zulip,hackerkid/zulip,synicalsyntax/zulip,synicalsyntax/zulip,rht/zulip,eeshangarg/zulip,kou/zulip,eeshangarg/zulip,synicalsyntax/zulip,shubhamdhama/zulip,showell/zulip,synicalsyntax/zulip,punchagan/zulip,brainwane/zulip,zulip/zulip,kou/zulip,eeshangarg/zulip,timabbott/zulip,kou/zulip,timabbott/zulip,andersk/zulip,showell/zulip,rht/zulip