* chore: add integration test for log parsing pipelines validation
* chore: add helpers for creating unauthorized, unavailable & not found api errors
* chore: return *model.APIError from logpipeline and agentConf functions
* chore: some cleanup
* chore: some more cleanup
* chore: one more round of cleanups
* fix: avoid pipeline builder panic if first op is disabled
* chore: use pipeline builder test to trigger getOperator panic
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Co-authored-by: Nityananda Gohain <nityanandagohain@gmail.com>