Fix remote locators filtering when whitelist provided

[juanlofer-eprosima]

Description

PR #3733 introduced a regression in which remote locators were being wrongly discarded when a whitelist is provided. In particular, the PR replaced several calls to transform_remote_locator (which for a remote locator performs no transformation and always return true irrespective of whether a whitelist is provided) by is_locator_allowed (which discards remote locators when a whitelist is provided).
This PR fixes the issue by checking if a locator is remote before going through the is_locator_allowed filter (every place where transform_remote_locator->is_locator_allowed change was introduced).

Contributor Checklist

• Commit messages follow the project guidelines.
• The code follows the style guidelines of this project.
• Tests that thoroughly check the new feature have been added/Regression tests checking the bug and its fix have been added; the added tests pass locally
• Any new/modified methods have been properly documented using Doxygen.
• Changes are ABI compatible.
• Changes are API compatible.
• N/A New feature has been added to the versions.md file (if applicable).
• N/A New feature has been documented/Current behavior is correctly described in the documentation.
• N/A Applicable backports have been included in the description.

Reviewer Checklist

• The PR has a milestone assigned.
• Check contributor checklist is correct.
• Check CI results: changes do not issue any warning.
• Check CI results: failing tests are unrelated with the changes.

[MiguelCompany]

Would be nice to have a regression test for this, but we will add it on a follow-up PR, since the fix has more urgency.

LGTM with green CI.

[MiguelCompany]

@richiprosima Please test this

[MiguelCompany]

@richiprosima Please test discovery-server, and also test mac