integrations: Rename HUBOT_INTEGRATIONS_LEGACY.
integrations: Rename HUBOT_INTEGRATIONS_LEGACY.

It is now simply called HUBOT_INTEGRATIONS.

Fixes #7402

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