Add fallback for "per-node" allocation strategy

[lhp-nemlig]

Component(s)

target allocator

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

The operator does not allow me to deploy a daemonset collector with any other allocation strategy than per-node. This is very reasonable, but if I add a prometheus scrape job that scrapes a single non-node-specific target it will not be allocated as that is currently the expected functionality of the "per-node" allocation strategy.

See below example of failure to deploy as daemonset with "consistent-hashing" allocation strategy.

Error: UPGRADE FAILED: an error occurred while rolling back the release. original upgrade error: cannot patch "opentelemetry" with kind OpenTelemetryCollector: admission webhook "vopentelemetrycollectorcreateupdatebeta.kb.io" denied the request: the OpenTelemetry Collector mode is set to daemonset, which must be used with target allocation strategy per-node

Describe the solution you'd like

I think there should be a fallback, ideally just using "consistent-hashing" or "least-weighted" for the leftover targets after "per-node" allocation is done.

Describe alternatives you've considered

No response

Additional context

The possibility of adding a fallback was talked about in this issue, but never acted upon.