trim docker container and add teardown logs

[atlv24]

let docker allocate ports to avoid a toctou bug between free_local_port() finding an available port and docker run binding to it, also trim the trailing newline from container id and log teardown errors for better visibility

[fslabs-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: loispostula

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• OWNERS [loispostula]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment