Reduce duplication introduced in `issuable_filters_present`

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/6497 introduces a issuable_filters_present helper that checks if any of the parameters used to filter Issuables are present. We then duplicate those keys in the app/views/shared/issuable/_filter.html.haml view.

https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/785 adds an extra layer by also checking for and duplicating the :weight key.

These keys should be defined in one place and then both of these should just use that. Ideally we can add :weight to the CE version and have parity between the two.

Added backstage technical debt ~131895 labels

Mentioned in issue #23568 (closed)

Added ~307502 label

Milestone changed to %8.15

Mentioned in issue #24854 (closed)

Added Deliverable label

Mentioned in merge request !7776 (merged)

!7776 (merged) addresses the duplication but not the :weight from EE, so this can't quite be closed yet.

Mentioned in commit 333e83a2

Removed ~307502 label

Status changed to closed by merge request gitlab-org/gitlab-ee!921

mentioned in merge request !14785