Per-group profiles aren't always used when Clustal colouring enabled

Per-group clustal shading should always reflect conservation in the local group. This works when the group is first created, but whenever a global colourscheme update triggers a refresh a group's colourscheme, the clustal shading shown for a group is based on the consensus profile for the alignment rather than just the sequences in the group.

Workarounds are unreliable - sometimes clicking in the group will change the clustal shading to reflect the local consensus, but the next global refresh will revert.

Noticed whilst testing [~geoff.barton]'s annexins exercise which includes explicit steps to give the system "a kick" by changing the colourscheme to another, then back to clustal, in order to workaround this problem.

Specific instances where this is seen: