disableIdentityMap fails with global context

[kristijanhusak]

Describe the bug
When using disableIdentityMap on the queries, I would expect that check for the Request context wouldn't trigger, because this flag will fork the entity manager every time

Stack trace

Error: ValidationError: Using global EntityManager instance methods for context specific actions is disallowed. If you need to work with the global instance's identity map, use `allowGlobalContext` configuration option or `fork()` instead.
    at Function.cannotUseGlobalContext (/src/node_modules/@mikro-orm/core/errors.js:83:16)
    at SqlEntityManager.getContext (/src/node_modules/@mikro-orm/core/EntityManager.js:665:44)
    at CustomerRepository.get em [as em] (/src/node_modules/@mikro-orm/knex/SqlEntityRepository.js:30:25)
    at CustomerRepository.findAll (/src/node_modules/@mikro-orm/core/entity/EntityRepository.js:63:21)
    at AppService.getCustomersFromScript (/src/src/app.service.ts:17:22)
    at execute (/src/scripts/test.ts:10:32)

To Reproduce
Steps to reproduce the behavior:

1. clone https://github.com/kristijanhusak/mikroorm-migration-issue
2. start with docker-compose up
3. Run the script with docker-compose exec api node_modules/.bin/ts-node scripts/test.ts

Expected behavior
Expected to be able to run the query because I passed disableIdentityMap: true to it. Code here.

Versions

Dependency	Version
node	16.13.0
typescript	4.55
mikro-orm	5.0.1
your-driver	postgres

[B4nan]

The problem is actually only if you use repository, as the validation is triggered by accessing the EM from a repository (which takes the one from context automatically), not by using the EM API directly.