RequestUtils getTableNames does not return multiple table names for sql join queries

[AlexanderKM]

For a query like

SELECT 
  table1.foo,
  table2.bar 
FROM 
  table1 
JOIN table2 ON table1.id = table2.id 
LIMIT 10;

the method RequestUtils#getTablesNames will only return the table1 as table names from the query.

For context of usage, we use this method to track metrics on the tables we are querying, so it is quite useful to us.

[yashmayya]

Fixed in #14554