fix(ui): Disable GKE Metadata as default Fixes: #11247, fixes #11260

[dvcanton]

Description of your changes:

• UI presents errors when deployed outside GKE as pointed in [frontend] Error on Kubeflow Pipelines Dashboard: 'No Healthy Upstream', '503 UC upstream_reset_before_response_started{connection_termination}' #11260.
• DISABLE_GKE_METADATA was set true as default and patched for GKE environments
• Tests were also adjusted

Fixes: #11247 & #11260

Duplicated from #11321 to include tests.

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[google-oss-prow]

Hi @dvcanton. Thanks for your PR.

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[hbelmiro]

@dvcanton can you take a look at the failing tests?

[dvcanton]

Hi @hbelmiro, thanks for the heads up. I have looked into the frontend server tests. They all pass locally now.

Test Suites: 10 passed, 10 total
Tests:       128 passed, 128 total
Snapshots:   12 passed, 12 total
Time:        8.185s, estimated 9s
Ran all test suites.

[HumairAK]

@dvcanton thank you!

/lgtm
/approve

[google-oss-prow]

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