reactions: Move legacy endpoint code further down in file.
reactions: Move legacy endpoint code further down in file.

This helps ensure that new contributors working on the reactions code
read the stuff we use now first.

timabbott/zulip,jackrzhang/zulip,jackrzhang/zulip,eeshangarg/zulip,jackrzhang/zulip,rishig/zulip,kou/zulip,synicalsyntax/zulip,hackerkid/zulip,timabbott/zulip,zulip/zulip,zulip/zulip,brainwane/zulip,dhcrzf/zulip,hackerkid/zulip,kou/zulip,synicalsyntax/zulip,mahim97/zulip,eeshangarg/zulip,shubhamdhama/zulip,eeshangarg/zulip,zulip/zulip,punchagan/zulip,mahim97/zulip,mahim97/zulip,timabbott/zulip,mahim97/zulip,zulip/zulip,zulip/zulip,jackrzhang/zulip,synicalsyntax/zulip,punchagan/zulip,rht/zulip,synicalsyntax/zulip,kou/zulip,kou/zulip,rht/zulip,dhcrzf/zulip,punchagan/zulip,showell/zulip,timabbott/zulip,tommyip/zulip,hackerkid/zulip,brainwane/zulip,tommyip/zulip,punchagan/zulip,tommyip/zulip,rht/zulip,brainwane/zulip,tommyip/zulip,showell/zulip,dhcrzf/zulip,synicalsyntax/zulip,andersk/zulip,timabbott/zulip,timabbott/zulip,shubhamdhama/zulip,punchagan/zulip,rishig/zulip,rht/zulip,hackerkid/zulip,eeshangarg/zulip,andersk/zulip,shubhamdhama/zulip,andersk/zulip,jackrzhang/zulip,synicalsyntax/zulip,zulip/zulip,rht/zulip,showell/zulip,mahim97/zulip,kou/zulip,rishig/zulip,kou/zulip,brainwane/zulip,dhcrzf/zulip,punchagan/zulip,shubhamdhama/zulip,jackrzhang/zulip,showell/zulip,shubhamdhama/zulip,punchagan/zulip,hackerkid/zulip,eeshangarg/zulip,jackrzhang/zulip,kou/zulip,shubhamdhama/zulip,rishig/zulip,timabbott/zulip,andersk/zulip,tommyip/zulip,tommyip/zulip,eeshangarg/zulip,dhcrzf/zulip,andersk/zulip,rishig/zulip,showell/zulip,hackerkid/zulip,andersk/zulip,rishig/zulip,dhcrzf/zulip,rht/zulip,showell/zulip,dhcrzf/zulip,eeshangarg/zulip,hackerkid/zulip,rht/zulip,brainwane/zulip,showell/zulip,andersk/zulip,rishig/zulip,synicalsyntax/zulip,tommyip/zulip,brainwane/zulip,brainwane/zulip,mahim97/zulip,zulip/zulip,shubhamdhama/zulip