tgc-revival: Fix retry logic in assert_test_files.go

[zli82016]

Modify the retry logic in
mmv1/third_party/tgc_next/test/assert_test_files.go
to ensure that tests are skipped only if all attempts failed due to "test data is unavailable". Currently, it skips if the last error was "test data is unavailable", which might be incorrect if previous attempts failed for other reasons.

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[modular-magician]

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terraform-google-conversion: Diff ( 1 file changed, 21 insertions(+), 12 deletions(-))

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

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Your PR generated some diffs in downstreams - here they are.

terraform-google-conversion: Diff ( 2 files changed, 24 insertions(+), 12 deletions(-))

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

Diff report

Your PR generated some diffs in downstreams - here they are.

terraform-google-conversion: Diff ( 2 files changed, 24 insertions(+), 12 deletions(-))

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

Diff report

Your PR generated some diffs in downstreams - here they are.

terraform-google-conversion: Diff ( 3 files changed, 28 insertions(+), 15 deletions(-))