feat: use new schema endpoint

[byashimov]

• Removes influxdb and autoscaler integration (not available)
• Adds new openapi-uc.json schema support
• Uses old schemas for removed schemas (like influxdb)
• Removes go client dependency, uses curl instead
• Removes goroutine usage. Still runs under 1 sec
• Removes MeasureExecutionTime, nothing to measure there

[byashimov]

The new schema is a bit different, that makes a diff on several fields. Not critical for my taste. The code can be further simplified in separate PRs and cut down to a simple code snippet:

• cobra is an overkill
• logger is a global object, which even causes false-positive linting issues
• other global variables
• lots of one-line functions
• etc

[byashimov]

TF generation example https://github.com/aiven/terraform-provider-aiven/pull/1887/files

[rriski]

Generally LGTM, some questions / comments