purge-old-deployments: Fix purging the symlinks etc.
purge-old-deployments: Fix purging the symlinks etc.

The recent rewrite of purge-old-deployments accidentally attempted to
purge the symlinks, sockets, lock, and other files in the deployment
directory.

The new version has been tested out in production successfully.

rishig/zulip,rht/zulip,hackerkid/zulip,synicalsyntax/zulip,mahim97/zulip,rishig/zulip,rishig/zulip,rht/zulip,showell/zulip,punchagan/zulip,rht/zulip,amanharitsh123/zulip,shubhamdhama/zulip,amanharitsh123/zulip,Galexrt/zulip,kou/zulip,amanharitsh123/zulip,tommyip/zulip,rishig/zulip,hackerkid/zulip,kou/zulip,dhcrzf/zulip,brainwane/zulip,dhcrzf/zulip,eeshangarg/zulip,tommyip/zulip,Galexrt/zulip,timabbott/zulip,dhcrzf/zulip,jackrzhang/zulip,hackerkid/zulip,kou/zulip,showell/zulip,zulip/zulip,timabbott/zulip,hackerkid/zulip,jackrzhang/zulip,brainwane/zulip,hackerkid/zulip,tommyip/zulip,amanharitsh123/zulip,Galexrt/zulip,showell/zulip,andersk/zulip,Galexrt/zulip,rht/zulip,synicalsyntax/zulip,dhcrzf/zulip,mahim97/zulip,jackrzhang/zulip,brainwane/zulip,brockwhittaker/zulip,dhcrzf/zulip,tommyip/zulip,Galexrt/zulip,andersk/zulip,rishig/zulip,shubhamdhama/zulip,zulip/zulip,jackrzhang/zulip,andersk/zulip,zulip/zulip,kou/zulip,jackrzhang/zulip,brainwane/zulip,brainwane/zulip,shubhamdhama/zulip,mahim97/zulip,jackrzhang/zulip,eeshangarg/zulip,tommyip/zulip,rishig/zulip,punchagan/zulip,punchagan/zulip,brainwane/zulip,punchagan/zulip,synicalsyntax/zulip,Galexrt/zulip,zulip/zulip,timabbott/zulip,shubhamdhama/zulip,eeshangarg/zulip,tommyip/zulip,verma-varsha/zulip,zulip/zulip,timabbott/zulip,jackrzhang/zulip,synicalsyntax/zulip,dhcrzf/zulip,eeshangarg/zulip,brockwhittaker/zulip,zulip/zulip,Galexrt/zulip,showell/zulip,mahim97/zulip,punchagan/zulip,shubhamdhama/zulip,verma-varsha/zulip,hackerkid/zulip,brockwhittaker/zulip,shubhamdhama/zulip,rht/zulip,andersk/zulip,brainwane/zulip,mahim97/zulip,amanharitsh123/zulip,amanharitsh123/zulip,tommyip/zulip,andersk/zulip,brockwhittaker/zulip,eeshangarg/zulip,eeshangarg/zulip,punchagan/zulip,verma-varsha/zulip,timabbott/zulip,timabbott/zulip,hackerkid/zulip,verma-varsha/zulip,showell/zulip,dhcrzf/zulip,rishig/zulip,punchagan/zulip,brockwhittaker/zulip,kou/zulip,synicalsyntax/zulip,mahim97/zulip,shubhamdhama/zulip,andersk/zulip,kou/zulip,rht/zulip,rht/zulip,zulip/zulip,andersk/zulip,kou/zulip,verma-varsha/zulip,timabbott/zulip,showell/zulip,synicalsyntax/zulip,verma-varsha/zulip,brockwhittaker/zulip,synicalsyntax/zulip,eeshangarg/zulip,showell/zulip