scrubber: remove AWS region assumption, tolerate negative max_project_size (#9636)

## Problem

First issues noticed when trying to run scrubber find-garbage on Azure:
- Azure staging contains projects with -1 set for max_project_size:
apparently the control plane treats this as a signed field.
- Scrubber code assumed that listing projects should filter to
aws-$REGION. This is no longer needed (per comment in the code) because
we know hit region-local APIs.

This PR doesn't make it work all the way (`init_remote` still assumes
S3), but these are necessary precursors.

## Summary of changes

- Change max-project_size from unsigned to signed
- Remove region filtering in favor of simply using the right region's
API (which we already do)

storage_scrubber/src/cloud_admin_api.rs

@@ -147,7 +147,7 @@ pub struct ProjectData {
     pub created_at: DateTime<Utc>,
     pub updated_at: DateTime<Utc>,
     pub pg_version: u32,
-    pub max_project_size: u64,
+    pub max_project_size: i64,
     pub remote_storage_size: u64,
     pub resident_size: u64,
     pub synthetic_storage_size: u64,
@@ -261,7 +261,7 @@ impl CloudAdminApiClient {
         }
     }
 
-    pub async fn list_projects(&self, region_id: String) -> Result<Vec<ProjectData>, Error> {
+    pub async fn list_projects(&self) -> Result<Vec<ProjectData>, Error> {
         let _permit = self
             .request_limiter
             .acquire()
@@ -318,7 +318,7 @@ impl CloudAdminApiClient {
 
             pagination_offset += response.data.len();
 
-            result.extend(response.data.drain(..).filter(|t| t.region_id == region_id));
+            result.append(&mut response.data);
 
             if pagination_offset >= response.total.unwrap_or(0) {
                 break;

storage_scrubber/src/garbage.rs

@@ -160,9 +160,7 @@ async fn find_garbage_inner(
     // Build a set of console-known tenants, for quickly eliminating known-active tenants without having
     // to issue O(N) console API requests.
     let console_projects: HashMap<TenantId, ProjectData> = cloud_admin_api_client
-        // FIXME: we can't just assume that all console's region ids are aws-<something>.  This hack
-        // will go away when we are talking to Control Plane APIs, which are per-region.
-        .list_projects(format!("aws-{}", bucket_config.region))
+        .list_projects()
         .await?
         .into_iter()
         .map(|t| (t.tenant, t))