Handling error on getting project id from google metadata server

[0daryo]

Adding error handling. I found adding test is difficult, if any good way please point.
Fix #751

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Patch Set 1:

(1 comment)

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This PR (HEAD: 2dd34a4) has been imported to Gerrit for code review.

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Patch Set 2:

(1 comment)

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This PR is being closed because golang.org/cl/626138 has been abandoned.

prefer https://pkg.go.dev/cloud.google.com/go/auth/credentials