[target allocator] Use Otel Go SDK for metrics reporting

[atoulme]

Component(s)

target allocator

Is your feature request related to a problem? Please describe.

Target Allocator uses prometheus metrics for metric reporting.

Describe the solution you'd like

Consider moving to otel go SDK.

Describe alternatives you've considered

No response

Additional context

No response

[swiatekm]

I'm definitely in favor of doing this, and in general improving the internal observability of the operator. I'd love to be able to trace reconciliation and webhook calls, for example. Logging is also a bit of a mess, and standardizing on the Otel SDK would help that.