Fixes #6314 Pass the error code instead of the retries count in the RUCSS strategy

[remyperona]

Description

Pass the error code instead of the retries count, as the expected second parameter of increment_retries() is the error code value.

Fixes #6314

Type of change

• Bug fix (non-breaking change which fixes an issue).

Is the solution different from the one proposed during the grooming?

No grooming for XS

Checklists

Generic development checklist

• My code follows the style guidelines of this project, with adapted comments and without new warnings.
• I have added unit and integration tests that prove my fix is effective or that my feature works.
• The CI passes locally with my changes (including unit tests, integration tests, linter).

Test summary

• I triggered all changed lines of code at least once without new errors/warnings/notices.
• I validated all Acceptance Criteria of the related issues. (If applicable, provide proof).

[MathieuLamiot]

I don't think this would need QA @wp-media/qa-team?

@Tabrisrp, if you tested it locally I think it is enough.

[vmanthos]

I don't think this would need QA

Agreed. 👍