Remove stale detection

[anthonyvdotbe]

What: remove stale detection, fixes #1324
Why:

• it's rarely used: Javadoc is typically generated in a CI/CD pipeline that starts from a blank slate
• it's broken, see Stale detection does not work: Javadoc generation is skipped when it should not #1324

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The following failed, but the failures have nothing to do with this PR:

The following builds failed:
*  MJAVADOC-498_modulepath\pom.xml
*  MJAVADOC-704_toolchains\pom.xml

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