Remove unnecessary `poll` method

[alopezz]

What does this PR do?

Removes poll method as it's redundant.

Motivation

QA for #12776.

The headers are already being set on parse_config which also includes the logic to add the token to the header only if the no_token config is set to false. poll was overwriting the headers and therefore has duplicate logic.

Additional Notes

Review checklist (to be filled by reviewers)

• [ ] Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• [ ] PR title must be written as a CHANGELOG entry (see why)
• [ ] Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
• [ ] PR must have changelog/ and integration/ labels attached

[codecov[bot]]

Codecov Report

Merging #12979 (c194e6d) into master (4a3ec76) will increase coverage by 0.01%. The diff coverage is n/a.

Flag	Coverage Δ
vault	95.46% <ø> (+1.04%)	:arrow_up:

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