refactor: Remove deduplicate_peerstates()

There's the `UNIQUE (acpeerstates.addr)` constraint since db v94.

src/peerstate.rs

@@ -811,30 +811,6 @@ enum PeerstateChange {
     Aeap(String),
 }
 
-/// Removes duplicate peerstates from `acpeerstates` database table.
-///
-/// Normally there should be no more than one peerstate per address.
-/// However, the database does not enforce this condition.
-///
-/// Previously there were bugs that caused creation of additional
-/// peerstates when existing peerstate could not be read due to a
-/// temporary database error or a failure to parse stored data.  This
-/// procedure fixes the problem by removing duplicate records.
-pub(crate) async fn deduplicate_peerstates(sql: &Sql) -> Result<()> {
-    sql.execute(
-        "DELETE FROM acpeerstates
-         WHERE id NOT IN (
-         SELECT MIN(id)
-         FROM acpeerstates
-         GROUP BY addr
-         )",
-        (),
-    )
-    .await?;
-
-    Ok(())
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;