Update git submodules

• Update extensions/DiscussionTools from branch 'REL1_43' to b301fae4d75ec7d05ffce42849fc99909ad36985
  • Notifications: Handle suppressed topic titles in notification
    
    EchoPresentationModelSection::getTruncatedSectionTitle() has a note that it should not be called if ::exists() returned false. Among the reason the section may not exist includes suppressing the revision where the topic title was added or edited.
    
    Add placeholder message text "(topic removed)", to be used in place of the unavailable topic title. This is analogous to "(user removed)" which would be shown along if the username is also suppressed.
    
    Bug: T378261 Change-Id: I6db0872b8724323a5e15eb6a262c2c3d0bdd630d (cherry picked from commit 4a25a985ffbc86b51fd04f4907774b6d162e2aa3)