Correct log message format in AbstractDriverManagerConnectionSource

The debug log message in AbstractDriverManagerConnectionSource had 4 placeholders but was supplied with 5 arguments.
This corrects the format string to match the argument count, resolving the warning.

Fixes #3828

Author: jhl221123

log4j-core/src/main/java/org/apache/logging/log4j/core/appender/db/jdbc/AbstractDriverManagerConnectionSource.java

@@ -160,7 +160,7 @@ public Connection getConnection() throws SQLException {
             connection = DriverManager.getConnection(actualConnectionString, toString(userName), toString(password));
         }
         LOGGER.debug(
-                "{} acquired connection for '{}': {} ({}{@})",
+                "{} acquired connection for '{}': {} ({}@{})",
                 getClass().getSimpleName(),
                 actualConnectionString,
                 connection,