Deprecate the $use_info_parser parameter to ExtensionParser::scanDirectory()

Problem/Motivation

Follow-up from #3490347-14: Replace ExtensionParser::scanDirectory() FileCache usage with InfoParser → (comments 14-16):

#14 @catch:

Do we ever call this code with $use_file_cache = FALSE? Maybe worth a follow-up to deprecate that code path if not.

#15 @alexpott:

Yeah we do. We do it when we scan for DB drivers see \Drupal\Core\Extension\DatabaseDriverList::getExtensionDiscovery() - not sure why FWIW. And we do when we generate a theme from a starterkit.- which makes sense to me.

#16 @catch:

Starterkit theme generation will only happen on the cli, which has (if it's enabled) it's own apcu cache which is not shared between cli processes, so if those are the only two cases I think we could simplify things and ditch it.

Steps to reproduce

Proposed resolution

Deprecate the parameter, which is now called $use_info_parser

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet