[BUG] ADNI-to-BIDS : Empty `fmap` folders generated for subjects without field maps

[Adam-Ismaili-92]

Describe The Bug
When using the ADNI-to-BIDS converter, if a subject does not have a field map, an empty fmap directory is created.

To Reproduce
Steps to reproduce the behavior:

1. Use the ADNI-to-BIDS converter on CI data, in particular on subjects 002_S_0413 and 116_S_4855.
2. Observe the empty fmap directories in the generated BIDS structure.

Expected Behavior
It is expected that there is no file for these subjects since they're not compliant, BUT empty fmap directories should not be created.

Screenshots

Desktop

• OS: Sequoia 15.7.1
• Clinica Version: 0.10.1

Additional Context
This error might be replicated on other converters.