templates: Remove development_environment safeguards for playgrounds.
templates: Remove development_environment safeguards for playgrounds.

Also with this we can mark #16432 as feature complete. There are a
couple of followups there for which we can open separate tasks/PRs.

Fixes: #16432

kou/zulip,kou/zulip,rht/zulip,eeshangarg/zulip,punchagan/zulip,eeshangarg/zulip,rht/zulip,punchagan/zulip,hackerkid/zulip,kou/zulip,eeshangarg/zulip,hackerkid/zulip,andersk/zulip,rht/zulip,kou/zulip,eeshangarg/zulip,hackerkid/zulip,punchagan/zulip,zulip/zulip,andersk/zulip,andersk/zulip,andersk/zulip,punchagan/zulip,punchagan/zulip,andersk/zulip,hackerkid/zulip,rht/zulip,eeshangarg/zulip,kou/zulip,punchagan/zulip,zulip/zulip,rht/zulip,rht/zulip,zulip/zulip,kou/zulip,kou/zulip,punchagan/zulip,andersk/zulip,hackerkid/zulip,rht/zulip,hackerkid/zulip,zulip/zulip,eeshangarg/zulip,andersk/zulip,zulip/zulip,eeshangarg/zulip,hackerkid/zulip,zulip/zulip,zulip/zulip