test(internal/testutil): fix race when accessing trace spans

[itizir]

Closes #10184, closes #10141.
Continuation of #5006.
Noticed in pipeline for #10153.

[itizir]

Ah, thanks for fixing it up! Sorry I missed those spots…

[itizir]

It's probably fine to return the pointer to the span data itself. What I'm not sure about is whether checking that there is no more than 1 span in that trace test is important... Let me know if you want me to tweak that some more, or feel free to do as you wish. :)

[quartzmo]

kokoro failure:

# cloud.google.com/go/bigquery [cloud.google.com/go/bigquery.test]
./oc_test.go:35:9: invalid operation: cannot call non-function te.Spans (variable of type []*"go.opencensus.io/trace".SpanData)
FAIL	cloud.google.com/go/bigquery [build failed]
?   	cloud.google.com/go/bigquery/analyticshub/apiv1/analyticshubpb	[no test files]
?   	cloud.google.com/go/bigquery/biglake/apiv1/biglakepb	[no test files]

[rahul2393]

kokoro failure:

# cloud.google.com/go/bigquery [cloud.google.com/go/bigquery.test]
./oc_test.go:35:9: invalid operation: cannot call non-function te.Spans (variable of type []*"go.opencensus.io/trace".SpanData)
FAIL	cloud.google.com/go/bigquery [build failed]
?   	cloud.google.com/go/bigquery/analyticshub/apiv1/analyticshubpb	[no test files]
?   	cloud.google.com/go/bigquery/biglake/apiv1/biglakepb	[no test files]

Yes, we need to first release the changes in cloud.google.com/go after which we need to make other relevant changes.

[harshachinta]

@rahul2393 I guess the PR title should be changed to internal instead of spanner for the release in that module. Also does test create a new release or should it be tagged as fix?