Security Reports: Permissions cleanup

What does this MR do?

Remove unused permission variable from Vuex store

Apparently we do not use these two variables canCreateIssuePermission and canCreateFeedbackPermission, so we can just get rid of them.

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Move permissions based on paths into vuex

Currently we define permissions in the MR Widget store and in the entrypoint for the pipelines view. This moves this definition into a VueX getter based on the actual paths.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team