safekeeper: remove unused partial_backup_enabled option (#8547)

## Problem
There is an unused safekeeper option `partial_backup_enabled`.

`partial_backup_enabled` was implemented in #6530, but this option was
always turned into enabled in #8022.

If you intended to keep this option for a specific reason, I will close
this PR.

## Summary of changes
I removed an unused safekeeper option `partial_backup_enabled`.

safekeeper/src/bin/safekeeper.rs

@@ -170,11 +170,6 @@ struct Args {
     /// still needed for existing replication connection.
     #[arg(long)]
     walsenders_keep_horizon: bool,
-    /// Enable partial backup. If disabled, safekeeper will not upload partial
-    /// segments to remote storage.
-    /// TODO: now partial backup is always enabled, remove this flag.
-    #[arg(long)]
-    partial_backup_enabled: bool,
     /// Controls how long backup will wait until uploading the partial segment.
     #[arg(long, value_parser = humantime::parse_duration, default_value = DEFAULT_PARTIAL_BACKUP_TIMEOUT, verbatim_doc_comment)]
     partial_backup_timeout: Duration,
@@ -347,7 +342,6 @@ async fn main() -> anyhow::Result<()> {
         sk_auth_token,
         current_thread_runtime: args.current_thread_runtime,
         walsenders_keep_horizon: args.walsenders_keep_horizon,
-        partial_backup_enabled: true,
         partial_backup_timeout: args.partial_backup_timeout,
         disable_periodic_broker_push: args.disable_periodic_broker_push,
         enable_offload: args.enable_offload,

safekeeper/src/lib.rs

@@ -93,7 +93,6 @@ pub struct SafeKeeperConf {
     pub sk_auth_token: Option<SecretString>,
     pub current_thread_runtime: bool,
     pub walsenders_keep_horizon: bool,
-    pub partial_backup_enabled: bool,
     pub partial_backup_timeout: Duration,
     pub disable_periodic_broker_push: bool,
     pub enable_offload: bool,
@@ -137,7 +136,6 @@ impl SafeKeeperConf {
             max_offloader_lag_bytes: defaults::DEFAULT_MAX_OFFLOADER_LAG_BYTES,
             current_thread_runtime: false,
             walsenders_keep_horizon: false,
-            partial_backup_enabled: false,
             partial_backup_timeout: Duration::from_secs(0),
             disable_periodic_broker_push: false,
             enable_offload: false,

safekeeper/src/timeline_manager.rs

@@ -544,8 +544,8 @@ impl Manager {
 
     /// Spawns partial WAL backup task if needed.
     async fn update_partial_backup(&mut self, state: &StateSnapshot) {
-        // check if partial backup is enabled and should be started
-        if !self.conf.is_wal_backup_enabled() || !self.conf.partial_backup_enabled {
+        // check if WAL backup is enabled and should be started
+        if !self.conf.is_wal_backup_enabled() {
             return;
         }
 

safekeeper/tests/walproposer_sim/safekeeper.rs

@@ -181,7 +181,6 @@ pub fn run_server(os: NodeOs, disk: Arc<SafekeeperDisk>) -> Result<()> {
         sk_auth_token: None,
         current_thread_runtime: false,
         walsenders_keep_horizon: false,
-        partial_backup_enabled: false,
         partial_backup_timeout: Duration::from_secs(0),
         disable_periodic_broker_push: false,
         enable_offload: false,