Send feedback to new api endpoint

[pixtron]

Describe the change

Use the api endpoint introduced with server version 2.7.x (see gyselroth/balloon/issues/412)

Current situation

Feedback gets sent to a fixed endpoint.

Should

Send the feedback to the new endpoint.

Check for limits like

• Body max size
• max attachment size
• max message size

Additional context

Add any other context about the problem here.

[pixtron]

Changes to the current fix:

• remove env.feedbackUrl and env.autoReportUrl completely
• if (clientConfig.has('blnUrl') ? clientConfig.get('blnUrl') : env.blnUrl) === undefined, try to get the blnUrl from last active Instance