refactor(pageserver): remove aux v1 configs (#9494)

## Problem

Part of https://github.com/neondatabase/neon/issues/8623

## Summary of changes

Removed all aux-v1 config processing code. Note that we persisted it
into the index part file, so we cannot really remove the field from
index part. I also kept the config item within the tenant config, but we
will not read it any more.

---------

Signed-off-by: Alex Chi Z <chi@neon.tech>

storage_controller/src/service.rs

@@ -4958,16 +4958,7 @@ impl Service {
                     stripe_size,
                 },
                 placement_policy: Some(PlacementPolicy::Attached(0)), // No secondaries, for convenient debug/hacking
-
-                // There is no way to know what the tenant's config was: revert to defaults
-                //
-                // TODO: remove `switch_aux_file_policy` once we finish auxv2 migration
-                //
-                // we write to both v1+v2 storage, so that the test case can use either storage format for testing
-                config: TenantConfig {
-                    switch_aux_file_policy: Some(models::AuxFilePolicy::CrossValidation),
-                    ..TenantConfig::default()
-                },
+                config: TenantConfig::default(),
             })
             .await?;