fix: make EnvAPIClient and docker-cli have same behavior towards env DOCKE…

[terloo]

Description

User will usually enable https when using docker-cli command line call remote docker-server.

But in skaffold, it will not enable TLS even user has env named DOCKER_TLS_VERIFY when get imageId from docker-server, that is different to behavior of docker-cli.

It cause a problem that people get a error Error response from daemon: Client sent an HTTP request to an HTTPS server. after they completed their docker-cli config and make useDockerCLI: true.

User facing changes (remove if N/A) When env DOCKER_TLS_VERIFY is not null, docker api client will enable TLS and read TLS file by order.

Follow-up Work (remove if N/A)

Maybe we should update the document?

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