Exclude public group milestones from counts in milestones dashboard

Closes #56332

See merge request gitlab-org/gitlab-ce!25230

(cherry picked from commit bd488bc2)

0f0bf2a2 Exclude public group milestones from counts

Add project when creating milestone in specs

We validate milestone is from the same
project/parent group as issuable ->
we need to set project in specs correctly

Improve methods names and specs organization

Adds to search ILIKE search for milestones title in:
  - Milestones dashboard
  - Group milestones page
  - Project milestones page

One of the steps to deprecate dashboard milestones.
Links do dashboard milestone are replaced with links for each
project milestone

Updates specs to use new rails5 format.

The old format:
`get :show, { some: params }, { some: headers }`

The new format:
`get :show, params: { some: params }, headers: { some: headers }`

Closes #33477