settings: Remove version field migration (#33711)

This reverts some parts of #33372, as it will break the settings for
users running stable and preview at the same time. We can add it back
once the changes make it to stable.

Release Notes:

- N/A

crates/migrator/src/migrations.rs

@@ -82,12 +82,6 @@ pub(crate) mod m_2025_06_16 {
     pub(crate) use settings::SETTINGS_PATTERNS;
 }
 
-pub(crate) mod m_2025_06_25 {
-    mod settings;
-
-    pub(crate) use settings::SETTINGS_PATTERNS;
-}
-
 pub(crate) mod m_2025_06_27 {
     mod settings;