Speed up specs for AlertManagement::Alert

What does this MR do?

Closes #227140 (closed)

Speed up specs for AlertManagement::Alert.

Before

Finished in 38.84 seconds (files took 52.61 seconds to load)
74 examples, 0 failures

[TEST PROF INFO] Factories usage

 Total: 107
 Total top-level: 61
 Total time: 8.7734s
 Total uniq factories: 5

   total   top-level   total time   top-level time                           name

      41          41      3.8132s          3.8132s         alert_management_alert
      32          18      7.8100s          4.9058s                        project
      32           0      1.9448s          0.0000s                      namespace
       1           1      0.0292s          0.0292s                        license
       1           1      0.0252s          0.0252s                    environment

After

Finished in 5.23 seconds (files took 32.34 seconds to load)
74 examples, 0 failures

[TEST PROF INFO] Factories usage

 Total: 12
 Total top-level: 10
 Total time: 1.0885s
 Total uniq factories: 5

   total   top-level   total time   top-level time                           name

       6           6      0.1050s          0.1050s         alert_management_alert
       2           2      0.9549s          0.9549s                        project
       2           0      0.1538s          0.0000s                      namespace
       1           1      0.0089s          0.0089s                        license
       1           1      0.0196s          0.0196s                    environment

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