Remove active column (#10335)

We don't need or want the `active` column. Remove it. Vlad pointed out
that this is safe.

Thanks to the separation of the schemata in earlier PRs, this is easy.

follow-up of #10205

Part of https://github.com/neondatabase/neon/issues/9981

storage_controller/migrations/2025-01-09-160454_safekeepers_remove_active/down.sql

@@ -0,0 +1,4 @@
+-- this sadly isn't a "true" revert of the migration, as the column is now at the end of the table.
+-- But preserving order is not a trivial operation.
+-- https://wiki.postgresql.org/wiki/Alter_column_position
+ALTER TABLE safekeepers ADD active BOOLEAN NOT NULL DEFAULT false;

storage_controller/migrations/2025-01-09-160454_safekeepers_remove_active/up.sql

@@ -0,0 +1 @@
+ALTER TABLE safekeepers DROP active;

storage_controller/src/persistence.rs

@@ -1258,7 +1258,6 @@ pub(crate) struct SafekeeperPersistence {
     pub(crate) version: i64,
     pub(crate) host: String,
     pub(crate) port: i32,
-    pub(crate) active: bool,
     pub(crate) http_port: i32,
     pub(crate) availability_zone_id: String,
     pub(crate) scheduling_policy: String,
@@ -1270,7 +1269,6 @@ impl SafekeeperPersistence {
             SkSchedulingPolicy::from_str(&self.scheduling_policy).map_err(|e| {
                 DatabaseError::Logical(format!("can't construct SkSchedulingPolicy: {e:?}"))
             })?;
-        // omit the `active` flag on purpose: it is deprecated.
         Ok(SafekeeperDescribeResponse {
             id: NodeId(self.id as u64),
             region_id: self.region_id.clone(),
@@ -1295,7 +1293,8 @@ pub(crate) struct SafekeeperUpsert {
     pub(crate) version: i64,
     pub(crate) host: String,
     pub(crate) port: i32,
-    pub(crate) active: bool,
+    /// The active flag will not be stored in the database and will be ignored.
+    pub(crate) active: Option<bool>,
     pub(crate) http_port: i32,
     pub(crate) availability_zone_id: String,
 }
@@ -1311,7 +1310,6 @@ impl SafekeeperUpsert {
             version: self.version,
             host: &self.host,
             port: self.port,
-            active: self.active,
             http_port: self.http_port,
             availability_zone_id: &self.availability_zone_id,
             // None means a wish to not update this column. We expose abilities to update it via other means.
@@ -1328,7 +1326,6 @@ struct InsertUpdateSafekeeper<'a> {
     version: i64,
     host: &'a str,
     port: i32,
-    active: bool,
     http_port: i32,
     availability_zone_id: &'a str,
     scheduling_policy: Option<&'a str>,

storage_controller/src/schema.rs

@@ -36,7 +36,6 @@ diesel::table! {
         version -> Int8,
         host -> Text,
         port -> Int4,
-        active -> Bool,
         http_port -> Int4,
         availability_zone_id -> Text,
         scheduling_policy -> Varchar,