Add Progressive failover mode to the failover connector

[akats7]

Description

This PR introduces the progressive failover mode to the failover connector. This failover mode is categorized by an iterative approach to failover routing, where on each export the connector will try to route to each exporter in the priority list, terminating at the first successful export.

  failover:
    priority_levels:
      - [traces/first]
      - [traces/second]
      - [traces/third]
    failover_mode: progressive

On each export the conenctor will try to route the data to traces/first, is that pipeline returns an error, it will then try to export to traces/second, if that succeeds the export is considered successful, if it fails it will then move on to trying traces/third. Regardless of the result of this export, the next export will still initially retry from traces/first.

PR #43094 is a pre-req for this PR as it introduces failover modes

Testing

Added the test TestProgressiveModeAlwaysTriesAllConsumers to test the progressive consume loop.

[github-actions]

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