Update git submodules
- Update ArticlePlaceholder from branch 'master' to 2c06b27ab20b8318596bb07a165f0f51dd0e5a21
- extension.json: Drop RL targets definitions, no longer honoured
Bug: T328497 Change-Id: I7184b0d717809675578069d5a6dce583de819de2
- extension.json: Drop RL targets definitions, no longer honoured