Fix the broken sample path in API

[IronPan]

Related change b476a84

/hold
Need investigate why test doesn't catch it.

/assign @numerology @gaoning777

---

This change is 

[numerology]

Sorry I'm not aware of this part of test.
May I ask where the related backend test lives? Thanks!

[numerology]

/lgtm

[IronPan]

@numerology All presubmit tests should fail because API server should in theory fail to start.

[IronPan]

With further investigation, it appears these lines didn't fully delete the pipeline's artifact/metadata GCE PD

pipelines/test/deploy-pipeline.sh

Line 55 in 701b90d

ks delete default -c pipeline

The PD backing metadata store is name with ${KFAPP}-storage-metadata-store
When reinstall the pipeline, the PD got reused and the metadata got recovered.

The API server decides if needs to load samples based on the HaveSamplesLoaded flag in the DB

pipelines/backend/src/apiserver/main.go

Line 145 in 701b90d

haveSamplesLoaded, err := resourceManager.HaveSamplesLoaded()

Because the DB's PD is reused, the flag is still true after reinstall, thus it skipped to load the samples.

[IronPan]

/hold cancel

[IronPan]

/approve

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[gaoning777]

With further investigation, it appears these lines didn't fully delete the pipeline's artifact/metadata GCE PD

pipelines/test/deploy-pipeline.sh

Line 55 in 701b90d

ks delete default -c pipeline

The PD backing metadata store is name with ${KFAPP}-storage-metadata-store
When reinstall the pipeline, the PD got reused and the metadata got recovered.

The API server decides if needs to load samples based on the HaveSamplesLoaded flag in the DB

pipelines/backend/src/apiserver/main.go

Line 145 in 701b90d

haveSamplesLoaded, err := resourceManager.HaveSamplesLoaded()

Because the DB's PD is reused, the flag is still true after reinstall, thus it skipped to load the samples.

Thanks for the investigation. This is really important for the test to catch the errors.