fix: terminate pgbouncer on compute suspend (#12153)

## Problem

PgBouncer does not terminate connections on a suspend:
https://github.com/neondatabase/cloud/issues/16282

## Summary of changes

1. Adds a pid file to store the pid of PgBouncer
2. Terminates connections on a compute suspend

---------

Co-authored-by: Alexey Kondratov <kondratov.aleksey@gmail.com>

control_plane/src/bin/neon_local.rs

@@ -672,6 +672,13 @@ struct EndpointStartCmdArgs {
     #[clap(short = 't', long, value_parser= humantime::parse_duration, help = "timeout until we fail the command")]
     #[arg(default_value = "90s")]
     start_timeout: Duration,
+
+    #[clap(
+        long,
+        help = "Run in development mode, skipping VM-specific operations like process termination",
+        action = clap::ArgAction::SetTrue
+    )]
+    dev: bool,
 }
 
 #[derive(clap::Args)]
@@ -1590,6 +1597,7 @@ async fn handle_endpoint(subcmd: &EndpointCmd, env: &local_env::LocalEnv) -> Res
                     stripe_size.0 as usize,
                     args.create_test_user,
                     args.start_timeout,
+                    args.dev,
                 )
                 .await?;
         }

control_plane/src/endpoint.rs

@@ -691,6 +691,7 @@ impl Endpoint {
         shard_stripe_size: usize,
         create_test_user: bool,
         start_timeout: Duration,
+        dev: bool,
     ) -> Result<()> {
         if self.status() == EndpointStatus::Running {
             anyhow::bail!("The endpoint is already running");
@@ -861,6 +862,10 @@ impl Endpoint {
             cmd.args(["--remote-ext-base-url", remote_ext_base_url]);
         }
 
+        if dev {
+            cmd.arg("--dev");
+        }
+
         let child = cmd.spawn()?;
         // set up a scopeguard to kill & wait for the child in case we panic or bail below
         let child = scopeguard::guard(child, |mut child| {