Change default for configWarningReuseIssue to false

[HonkingGoose]

Describe the proposed change(s).

Todos:

• Set default setting for configWarningReuseIssue to false in the code.
• Update the tests.
• Update the configWarningReuseIssue config option docs.
• Update outdated references to configWarningReuseIssue in the docs.
• Write release note entry (developer commentary) for the v39 changelog:
  • Explain new default behavior
  • Explain why we changed the default: to stop users missing the configuration error warnings in a old re-opened issue.
  • Users can opt-out of this change, by setting configWarningReuseIssue to true, to keep the old behavior.

Creating this issue after approval from @rarkins in:

• Forking Renovate, why re-open old config error issue, and why no config warning on Dependency Dashboard? #29132 (reply in thread)

[RahulGautamSingh]

Should we pass it to v39?