import script: Delete medium sized avatars if it exists.
import script: Delete medium sized avatars if it exists.

Deletion of medium sized image is done if it exists before calling the
function 'ensure_medium_avatar_image', to avoid potentially confusing
problems with left-over medium-size avatar images from a previous run
being used when repeatedly importing the same realm in a development
environment..

Fixes #8949.

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