fix: databasetesting.CreateForDevel() now tries to connect for 10s

There seems to be a race between when the Docker PG healthcheck passes,
and when the Docker port becomes available:

    trace: exec: cd . && docker inspect --format \{\{.State.Health.Status}} ftl-db-1
    debug: Postgres DSN: ***localhost:54320/ftl?sslmode=disable
    ftl: error: failed to connect to `host=localhost user=postgres database=`: failed to receive message (unexpected EOF)

It's not clear if that's a deficiency in Docker, or perhaps pg_isready
is only checking the Unix socket and not the TCP port, and there's some
delay between the two becoming available. Either way, this should solve
it.

backend/controller/sql/databasetesting/devel.go

@@ -3,29 +3,45 @@ package databasetesting
 import (
 	"context"
 	"fmt"
+	"time"
 
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgxpool"
 
+	"github.com/TBD54566975/ftl/backend/common/log"
 	"github.com/TBD54566975/ftl/backend/controller/sql"
 )
 
 // CreateForDevel creates and migrates a new database for development or testing.
 //
 // If "recreate" is true, the database will be dropped and recreated.
 func CreateForDevel(ctx context.Context, dsn string, recreate bool) (*pgxpool.Pool, error) {
+	logger := log.FromContext(ctx)
 	config, err := pgx.ParseConfig(dsn)
 	if err != nil {
 		return nil, err
 	}
 
 	noDBDSN := config.Copy()
 	noDBDSN.Database = ""
-	conn, err := pgx.ConnectConfig(ctx, noDBDSN)
-	if err != nil {
-		return nil, err
+	var conn *pgx.Conn
+	for i := 0; i < 10; i++ {
+		conn, err = pgx.ConnectConfig(ctx, noDBDSN)
+		if err == nil {
+			defer conn.Close(ctx)
+			break
+		}
+		logger.Debugf("Waiting for database to be ready: %v", err)
+		select {
+		case <-ctx.Done():
+			return nil, ctx.Err()
+
+		case <-time.After(1 * time.Second):
+		}
+	}
+	if conn == nil {
+		return nil, fmt.Errorf("database not ready after 10 tries: %w", err)
 	}
-	defer conn.Close(ctx)
 
 	if recreate {
 		// Terminate any dangling connections.