Ensure proper cleanup of the database connection in createSchema

[cuca24]

fixes #4255
Potentially fixes the #4479

As per TypeORM documentation Disconnection (closing all connections in the pool) occurs when the destroy method is called.

All methods in MysqlRecordManager contains destroy call except createSchema call.

I tested locally and this keeps connection to 0 after the calls.

[HenryHengZJ]

thanks! with this fix, have you tried testing again and see if that free up the ram?

[cuca24]

@HenryHengZJ
I tested both with this fix and without this fix. And i can confirm that this fix also fixes issue i reported in #4479

Without a fix memory consumption rises constantly, while with the fix, it always returns to the same memory usage after i run thousands api requests. I even run with 20 parallel processes at once and it seems to be working ok. Memory does rises a bit but it's not leaking (it's does not rise constantly) and after it finishes it returns to the memory consumption that was before making upsert api calls.

[HenryHengZJ]

are you able to build and run it? because await this.getDataSource('createSchema') is throwing an error, getDataSource doesnt take in any input parameter

[cuca24]

@HenryHengZJ yes it should be const dataSource = await this.getDataSource(). without additional param. I used it for testing purposes but forgot to clean it out.