Local extensions are not indexed anymore by the extension index

Since XWiki 16.8.0, the extension index job doesn't add the extensions found in the local extension repository anymore, even when the request asks for it (which is the case for the first indexing job executed at startup).

Since the indexing of remote extensions skips the versions which are available locally (expecting them to be indexed as local extensions), the consequence is that a version present in the local extension repository (which includes all installed extensions) is not added to the extension index, unless it got there in some other way (like the validation of compatible versions). This includes:

• an extension coming from a non searchable repository (like Maven Central) or from an uploaded file
• an extension downloaded from a searchable repository, when the local version is also the last remote version

Such extensions are missing from everything relying on the extension index, such as the extensions search in the Extension Manager or the list of installed extensions with security vulnerabilities.

The reason is that the call to the method indexing local extensions in ExtensionIndexJob was commented out as part of XCOMMONS-3051 (most probably a debug leftover), and the method itself was later removed as unused.