[Other] Remove explicit mentions of non-bundled dependencies from `LICENSE.txt`

### Describe the bug, including details regarding any error messages, version, and platform.

This is a follow up to https://github.com/apache/arrow/pull/38660#discussion_r1525651207.

While working on [integrating the MATLAB bindings into the project's release infrastructure](https://github.com/apache/arrow/pull/38660), we noticed that certain **non**-bundled dependencies (e.g. zlib) are mentioned in LICENSE.txt. However, based on the ASF"s documentation for ["Assembling LICENSE and NOTICES Files"](https://infra.apache.org/licensing-howto.html), it seems like [only **bundled** dependencies](https://infra.apache.org/licensing-howto.html#permissive-deps) should be explicitly mentioned in [`LICENSE.txt`](https://github.com/apache/arrow/blob/main/LICENSE.txt).

**Note**: There is currently no "Licensing" component for issues, so we chose "Other" as that seemed like the most reasonable option for categorizing this issue. Perhaps, we should add a "Licensing" component, as well?

### Component(s)

Other