test-all: Print a colorful notice on startup discouraging use.
test-all: Print a colorful notice on startup discouraging use.

The test-all tool is useful if you want to be really sure everything
passes, but it's almost always better to run a smaller subsuite when
doing active development, and just run test-all (or CI) at the end.

Our docs already covered this issue well, but this presents the idea
in a place one is definitely looking at when running test-all.

shubhamdhama/zulip,shubhamdhama/zulip,punchagan/zulip,timabbott/zulip,rht/zulip,andersk/zulip,hackerkid/zulip,synicalsyntax/zulip,shubhamdhama/zulip,andersk/zulip,eeshangarg/zulip,rht/zulip,showell/zulip,zulip/zulip,kou/zulip,brainwane/zulip,punchagan/zulip,kou/zulip,andersk/zulip,brainwane/zulip,synicalsyntax/zulip,timabbott/zulip,punchagan/zulip,rht/zulip,eeshangarg/zulip,synicalsyntax/zulip,synicalsyntax/zulip,rht/zulip,timabbott/zulip,rht/zulip,zulip/zulip,punchagan/zulip,synicalsyntax/zulip,zulip/zulip,showell/zulip,eeshangarg/zulip,showell/zulip,showell/zulip,kou/zulip,punchagan/zulip,showell/zulip,shubhamdhama/zulip,brainwane/zulip,kou/zulip,timabbott/zulip,eeshangarg/zulip,hackerkid/zulip,rht/zulip,brainwane/zulip,shubhamdhama/zulip,andersk/zulip,timabbott/zulip,shubhamdhama/zulip,rht/zulip,eeshangarg/zulip,hackerkid/zulip,hackerkid/zulip,timabbott/zulip,brainwane/zulip,hackerkid/zulip,timabbott/zulip,hackerkid/zulip,synicalsyntax/zulip,eeshangarg/zulip,punchagan/zulip,brainwane/zulip,synicalsyntax/zulip,andersk/zulip,zulip/zulip,brainwane/zulip,kou/zulip,zulip/zulip,zulip/zulip,showell/zulip,andersk/zulip,eeshangarg/zulip,kou/zulip,punchagan/zulip,zulip/zulip,andersk/zulip,kou/zulip,hackerkid/zulip,shubhamdhama/zulip,showell/zulip