Move the database configuration to a new section

[kelechi2020]

closes: 15930

This PR moves the following configurations from [core] to the new [database] section.

• sql_alchemy_conn
• sql_engine_encoding
• sql_engine_collation_for_ids
• sql_alchemy_pool_enabled
• sql_alchemy_pool_size
• sql_alchemy_max_overflow
• sql_alchemy_pool_recycle
• sql_alchemy_pool_pre_ping
• sql_alchemy_schema
• sql_alchemy_connect_args
• load_default_connections
• max_db_retries

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