chore: improve performance of 'GetLatestWorkspaceBuildsByWorkspaceIDs' (#19452)

Closes https://github.com/coder/internal/issues/716

This prevents a scan over the entire `workspace_build` table by removing
a `join`. This is still imperfect as we are still scanning over the
number of builds for the workspaces in the arguments. Ideally we would
have some index or something precomputed. Then we could skip scanning
over the builds for the correct workspaces that are not the latest.

coderd/database/queries.sql.go

@@ -18983,20 +18983,15 @@ func (q *sqlQuerier) GetLatestWorkspaceBuildByWorkspaceID(ctx context.Context, w
 }
 
 const getLatestWorkspaceBuildsByWorkspaceIDs = `-- name: GetLatestWorkspaceBuildsByWorkspaceIDs :many
-SELECT wb.id, wb.created_at, wb.updated_at, wb.workspace_id, wb.template_version_id, wb.build_number, wb.transition, wb.initiator_id, wb.provisioner_state, wb.job_id, wb.deadline, wb.reason, wb.daily_cost, wb.max_deadline, wb.template_version_preset_id, wb.has_ai_task, wb.ai_task_sidebar_app_id, wb.has_external_agent, wb.initiator_by_avatar_url, wb.initiator_by_username, wb.initiator_by_name
-FROM (
-    SELECT
-        workspace_id, MAX(build_number) as max_build_number
-    FROM
-		workspace_build_with_user AS workspace_builds
-    WHERE
-        workspace_id = ANY($1 :: uuid [ ])
-    GROUP BY
-        workspace_id
-) m
-JOIN
-	 workspace_build_with_user AS wb
-ON m.workspace_id = wb.workspace_id AND m.max_build_number = wb.build_number
+SELECT
+	DISTINCT ON (workspace_id)
+	id, created_at, updated_at, workspace_id, template_version_id, build_number, transition, initiator_id, provisioner_state, job_id, deadline, reason, daily_cost, max_deadline, template_version_preset_id, has_ai_task, ai_task_sidebar_app_id, has_external_agent, initiator_by_avatar_url, initiator_by_username, initiator_by_name
+FROM
+	workspace_build_with_user AS workspace_builds
+WHERE
+	workspace_id = ANY($1 :: uuid [ ])
+ORDER BY
+	workspace_id, build_number DESC -- latest first
 `
 
 func (q *sqlQuerier) GetLatestWorkspaceBuildsByWorkspaceIDs(ctx context.Context, ids []uuid.UUID) ([]WorkspaceBuild, error) {