Fix pgbouncer settings update:

- Start pgbouncer in VM from postgres user, to allow connection to
pgbouncer admin console.
- Remove unused compute_ctl options --pgbouncer-connstr
and --pgbouncer-ini-path.
- Fix and cleanup code of connection to pgbouncer, add retries
because pgbouncer may not be instantly ready when compute_ctl starts.

compute_tools/src/bin/compute_ctl.rs

@@ -32,8 +32,6 @@
 //!             -S /var/db/postgres/specs/current.json \
 //!             -b /usr/local/bin/postgres \
 //!             -r http://pg-ext-s3-gateway \
-//!             --pgbouncer-connstr 'host=localhost port=6432 dbname=pgbouncer user=cloud_admin sslmode=disable'
-//!             --pgbouncer-ini-path /etc/pgbouncer.ini \
 //! ```
 //!
 use std::collections::HashMap;
@@ -112,9 +110,6 @@ fn main() -> Result<()> {
     let spec_json = matches.get_one::<String>("spec");
     let spec_path = matches.get_one::<String>("spec-path");
 
-    let pgbouncer_connstr = matches.get_one::<String>("pgbouncer-connstr");
-    let pgbouncer_ini_path = matches.get_one::<String>("pgbouncer-ini-path");
-
     // Extract OpenTelemetry context for the startup actions from the
     // TRACEPARENT and TRACESTATE env variables, and attach it to the current
     // tracing context.
@@ -225,8 +220,6 @@ fn main() -> Result<()> {
         ext_remote_storage: ext_remote_storage.map(|s| s.to_string()),
         ext_download_progress: RwLock::new(HashMap::new()),
         build_tag,
-        pgbouncer_connstr: pgbouncer_connstr.map(|s| s.to_string()),
-        pgbouncer_ini_path: pgbouncer_ini_path.map(|s| s.to_string()),
     };
     let compute = Arc::new(compute_node);
 
@@ -523,23 +516,6 @@ fn cli() -> clap::Command {
                 )
                 .value_name("FILECACHE_CONNSTR"),
         )
-        .arg(
-            Arg::new("pgbouncer-connstr")
-                .long("pgbouncer-connstr")
-                .default_value(
-                    "host=localhost port=6432 dbname=pgbouncer user=cloud_admin sslmode=disable",
-                )
-                .value_name("PGBOUNCER_CONNSTR"),
-        )
-        .arg(
-            Arg::new("pgbouncer-ini-path")
-                .long("pgbouncer-ini-path")
-                // Note: this doesn't match current path for pgbouncer.ini.
-                // Until we fix it, we need to pass the path explicitly
-                // or this will be effectively no-op.
-                .default_value("/etc/pgbouncer.ini")
-                .value_name("PGBOUNCER_INI_PATH"),
-        )
 }
 
 /// When compute_ctl is killed, send also termination signal to sync-safekeepers