Revert "fix: align backend_tls default value with example config (#7496)"

This reverts commit 83932c8c9e.

src/common/meta/src/kv_backend/rds/postgres.rs

@@ -868,8 +868,6 @@ impl PgStore {
         let client = match pool.get().await {
             Ok(client) => client,
             Err(e) => {
-                // We need to log the debug for the error to help diagnose the issue.
-                common_telemetry::error!(e; "Failed to get Postgres connection.");
                 return GetPostgresConnectionSnafu {
                     reason: e.to_string(),
                 }

src/meta-srv/src/metasrv.rs

@@ -299,7 +299,7 @@ impl Default for MetasrvOptions {
             #[allow(deprecated)]
             server_addr: String::new(),
             store_addrs: vec!["127.0.0.1:2379".to_string()],
-            backend_tls: Some(TlsOption::prefer()),
+            backend_tls: None,
             selector: SelectorType::default(),
             enable_region_failover: false,
             heartbeat_interval: distributed_time_constants::BASE_HEARTBEAT_INTERVAL,

src/servers/src/tls.rs

@@ -91,17 +91,6 @@ impl TlsOption {
         tls_option
     }
 
-    /// Creates a new TLS option with the prefer mode.
-    pub fn prefer() -> Self {
-        Self {
-            mode: TlsMode::Prefer,
-            cert_path: String::new(),
-            key_path: String::new(),
-            ca_cert_path: String::new(),
-            watch: false,
-        }
-    }
-
     /// Validates the TLS configuration.
     ///
     /// Returns an error if: