billing: Rename customer_with_active_subscription in fixture generation.
billing: Rename customer_with_active_subscription in fixture generation.

Fixes regression introduced in 79dddd5.

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