Fix .airflowignore negation patterns for subdirectories

[seruman]

Fixes negation patterns in .airflowignore not working for subdirectories when
using glob syntax.

From docs;

https://airflow.apache.org/docs/apache-airflow/stable/core-concepts/dags.html#airflowignore
A pattern can be negated by prefixing with !. Patterns are evaluated in order so a negation can override a previously defined pattern in the same file or patterns defined in a parent directory.

Taken from #58636:

.
├── dag.py
├── ignored.py
└── subdir/
  ├── dag.py
  └── ignored.py

# .airflowignore

*
!dag.py
!subdir/dag.py

With the above setup, only dag.py and subdir/dag.py are included. Files
like ignored.py and subdir/ignored.py and the rest stays ignored.

Previously, the * pattern would match and prune subdir before the negation
patterns could be evaluated.

The fix checks if any negation pattern exists in the rules. If a directory
would be ignored but there are negation patterns, the directory is not pruned,
allowing file-level matching to decide what gets included.

Closes: #58636

---

^ Add meaningful description above
Read the Pull Request Guidelines for more information.
In case of fundamental code changes, an Airflow Improvement Proposal (AIP) is needed.
In case of a new dependency, check compliance with the ASF 3rd Party License Policy.
In case of backwards incompatible changes please leave a note in a newsfragment file, named {pr_number}.significant.rst or {issue_number}.significant.rst, in airflow-core/newsfragments.

[henry3260]

Hi @seruman , thanks for submitting this PR!

I was already assigned to this issue #58636 and have just pushed my own solution here: (#58740).

To avoid redundant work and merge conflicts, I recommend closing this PR so we can focus the review on mine. Feel free to leave any comments or suggestions on my PR if you spot anything! Thanks!

[seruman]

My bad, have not noticed it.