Fix the environment filter of Deployments Finder

Currently, the environment filter infers that the assocaited
environments can be multiple, but it's not the case.
This commit fixes the query to convince PostgreSQL that
the environment is always one.

app/models/deployment.rb

@@ -33,7 +33,8 @@ class Deployment < ApplicationRecord
 
   scope :for_environment, -> (environment) { where(environment_id: environment) }
   scope :for_environment_name, -> (project, name) do
-    where(environment_id: Environment.select(:id).where(project: project, name: name))
+    where('deployments.environment_id = (?)',
+      Environment.select(:id).where(project: project, name: name).limit(1))
   end
 
   scope :for_status, -> (status) { where(status: status) }

changelogs/unreleased/fix-deployment-finder-environment-in-query.yml

+---
+title: Fix environment filter of Deployments Finder
+merge_request: 61564
+author:
+type: performance