Increase test coverage in src/folio_migration_tools/marc_rules_transformation/rules_mapper_holdings.py

[fontanka16]

Description

Your task is to create happy path tests for the methods remove_from_id_map and set_default_call_number_type_if_empty in rules_mapper_holdings.py.
You will need to mock RulesMapperHoldings.

DoD

• You have read the testing section in https://github.com/FOLIO-FSE/folio_migration_tools/blob/main/CONTRIBUTING.md#testing
• You have created a branch from this issue and checked it out locally
• You have run the entire test suite as described in Contributing.md making sure the code works before you start working on it
• You have written the test outlined in the description above
• You have successfully run the test
• You have performed all steps outlined in the Github workflow section in the Contributing.md file, including creating a pull request.