Adapt security collector template name to webprofiler conventions

| Q             | A
| ------------- | ---
| Bug fix?      | no, but syntax consistency & future compatibility(?)
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | fabpot/Twig#1156 which was reverted but will be merged in the future
| License       | MIT


Use Twig namespace syntax instead of bundle syntax for security webprofiler template to be consistent with @WebProfiler template names.