Don't close DataSource with bad connection

- Attempt to recursively obtain a valid connection.
  This could lead to StackOverFlowException if db goes
  down, so that is caught.

Affects issues:
- Possibly fixed #1458

Plan/common/src/main/java/com/djrapitops/plan/storage/database/MySQLDB.java

@@ -127,13 +127,10 @@ public class MySQLDB extends SQLDB {
         Connection connection = dataSource.getConnection();
         if (!connection.isValid(5)) {
             connection.close();
-            dataSource.close();
             try {
-                setupDataSource();
-                // get new connection after restarting pool
-                connection = dataSource.getConnection();
-            } catch (DBInitException e) {
-                throw new DBOpException("Failed to restart DataSource after a connection was invalid: " + e.getMessage(), e);
+                return getConnection();
+            } catch (StackOverflowError databaseHasGoneDown) {
+                throw new DBOpException("Valid connection could not be fetched (Is MySQL down?) - attempted until StackOverflowError occurred.", databaseHasGoneDown);
             }
         }
         if (connection.getAutoCommit()) connection.setAutoCommit(false);