fix: Revert user-agent for docker cli client

[idsulik]

What I did
Removed custom user-agent for docker cli client(that was added within this PR), because docker docker desktop's does specific logic depending on the user agent. The latest docker compose takes 3 seconds to do a request to the docker daemon.
More details here docker/for-mac#7575 (comment)

I also tried the ping method(internal/desktop/client.go:78) with the new user agent and it works fine, so decided to left it as is.

Related issue
#12511

p.s. I'm not sure should we change logic here or the docker desktop should start accepting the new user-agent, feel free to close this PR in case of the second case

@milas fyi

[milas]

fyi I am no longer a Docker Compose maintainer / Docker Inc employee, so I can't really help here

[idsulik]

closing it because of this comment docker/for-mac#7575 (comment)

Thanks for testing! No, docker compose shouldn't update; or at least, shouldn't have to because this looks like a regression in the docker desktop API proxy.

I recall that the fix at the time was fixing the immediate issue, but that there was a tracking ticket to look at ways to remove that conditional code altogether (having conditional code based on user-agent definitely isn't ideal! I recall the alternative was a much more involved change, so as things go, that was left as a backlog item).

I already posted this issue internally, but I'll try to find the right person to look into this after the weekend.