Add installed state metrics for Cilium cluster application

What does this MR do?

With the addition of the model for the Cilium cluster application we want to collect metrics for it's installation state. This MR add a new clusters_applications_cilium metric which is similar to other metrics we have for cluster applications.

related to #214028 (closed)

DB query:

[1] pry(main)> Clusters::Applications::Cilium.available
  Clusters::Applications::Cilium Load (0.4ms)  SELECT "clusters_applications_cilium".* FROM "clusters_applications_cilium" WHERE "clusters_applications_cilium"."status" IN (3, 5)

plan:

 Seq Scan on public.clusters_applications_cilium  (cost=0.00..50.62 rows=8 width=68) (actual time=0.004..0.004 rows=0 loops=1)
   Filter: (clusters_applications_cilium.status = ANY ('{3,5}'::integer[]))
   Rows Removed by Filter: 0

time:

Time: 0.118 ms
  - planning: 0.090 ms
  - execution: 0.028 ms
    - I/O read: 0.000 ms
    - I/O write: 0.000 ms

Shared buffers:
  - hits: 0 from the buffer pool
  - reads: 0 from the OS file cache, including disk I/O
  - dirtied: 0
  - writes: 0

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability 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
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

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