Fix security group modal header overflow

If you go to Edit Instance > Security Group
The two headers "All Security Groups" and "Instance Security Groups"
overflow when translated

Change-Id: I5acd0e4670a6595e6f38ba7f17371b6329ed5836
Closes-Bug:#1288402
(cherry picked from commit 0048dfc6a84c1e6c22c99d01a448b3ed8cf2de14)