[7.x] systemtest: update opentelemetry-go (backport #6124)

[mergify]

This is an automatic backport of pull request #6124 done by Mergify.
Cherry-pick of 117ca87 has failed:

On branch mergify/bp/7.x/pr-6124
Your branch is up to date with 'origin/7.x'.

You are currently cherry-picking commit 117ca878.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   systemtest/approvals/TestOTLPGRPCMetrics.approved.json
	modified:   systemtest/approvals/TestOTLPGRPCTraces/data_streams_disabled.approved.json
	modified:   systemtest/approvals/TestOTLPGRPCTraces/data_streams_enabled.approved.json
	modified:   systemtest/benchtest/clients.go
	modified:   systemtest/logging_test.go
	modified:   systemtest/otlp_test.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   systemtest/go.mod
	both modified:   systemtest/go.sum

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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• Start Time: 2021-09-23T03:16:18.916+0000

• Duration: 51 min 50 sec

• Commit: c2c7380

Test stats 🧪

Test	Results
Failed	0
Passed	4475
Skipped	15
Total	4490