Harden users_created usage data queries

What does this MR do?

Harden users_created usage data queries

Query MIN

SELECT MIN("users"."id") FROM "users" WHERE "users"."created_at" BETWEEN '2020-05-08 12:07:41.738136' AND '2020-06-05 12:07:41.738208';

Before: https://explain.depesz.com/s/W4os 18 seconds

After: Precomputed value

Query MAX

SELECT MAX("users"."id") FROM "users" WHERE "users"."created_at" BETWEEN '2020-05-08 12:07:41.738136' AND '2020-06-05 12:07:41.738208';

Before: https://explain.depesz.com/s/9ELwk <10 ms

After: Precomputed value

Query COUNT

SELECT COUNT("users"."id") FROM "users" WHERE "users"."created_at" BETWEEN '2020-05-08 12:14:46.058262' AND '2020-06-05 12:14:46.058335' AND "users"."id" BETWEEN 1 AND 10000;

Before: https://explain.depesz.com/s/7Hnl < 250 ms

After:

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 #220478 (closed)