Improve environments queries for performance

What does this MR do?

Improves Projects::EnvironmentsController#index.json performance with reducing SQL queries.

current queries:

SELECT COUNT(*) FROM "environments" WHERE "environments"."project_id" = $1 AND ("environments"."state" IN ('stopped'))
SELECT COUNT(*) FROM "environments" WHERE "environments"."project_id" = $1 AND ("environments"."state" IN ('available'))

proposed query:

SELECT COUNT("environments"."id") AS count_id, "environments"."state" AS environments_state FROM "environments" WHERE "environments"."project_id" = $1 GROUP BY "environments"."state" 

What are the relevant issue numbers?

Closes #58660 (moved)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• [n/a] Documentation created/updated via this MR
• [n/a] Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• [n/a] Security reports checked/validated by reviewer