Improve query to retrieve job artifacts with files stored locally

What does this MR do?

Remove the check for file_store being null since we already have a default value set for the file_store column in the ci_job_artifacts table see !34568 (merged).

Query plan

• Before

  SELECT
  	"ci_job_artifacts".*
  FROM
  	"ci_job_artifacts"
  WHERE ("ci_job_artifacts"."file_store" = 1
  	OR "ci_job_artifacts"."file_store" IS NULL);

  Plan with execution: https://explain.depesz.com/s/T83b

  Summary:

  Time: 5.015 min
    - planning: 0.169 ms
    - execution: 5.015 min
      - I/O read: 4.933 min
      - I/O write: 0.000 ms
  
  Shared buffers:
    - hits: 31371 (~245.10 MiB) from the buffer pool
    - reads: 249009 (~1.90 GiB) from the OS file cache, including disk I/O
    - dirtied: 96808 (~756.30 MiB)
    - writes: 0

• After

  SELECT
  	"ci_job_artifacts".*
  FROM
  	"ci_job_artifacts"
  WHERE
  	"ci_job_artifacts"."file_store" = 1;

  Plan with execution: https://explain.depesz.com/s/F4TS

  Summary:

  Time: 43.056 s
    - planning: 0.208 ms
    - execution: 43.056 s
      - I/O read: 41.242 s
      - I/O write: 237.318 ms
  
  Shared buffers:
    - hits: 294283 (~2.20 GiB) from the buffer pool
    - reads: 142276 (~1.10 GiB) from the OS file cache, including disk I/O
    - dirtied: 21674 (~169.30 MiB)
    - writes: 6882 (~53.80 MiB)

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

Closes #223788 (closed)