Removed unnecessary filter rejecting unsafe URLs

[pbking]

It seems that the filter to allow unsafe URLs was unnecessary. I believe it was added to get the plugin to work as expected in a docker container (wp-env) and another solution was ultimately used to make that work anyway.

With this filter removed there should be no more problems as described in #584

Fixes #584

NOTE: I was unable to reproduce this with the steps provided in #584. However I'm sure it could be triggered given the function could be constructed multiple times with that logic.

To Test:

• Edit a template with media to be saved. (For example add an image block to the index template)
• Save the template
• Save the theme (make sure "Localize Images" is selected).
• Note that the image asset is saved in the /asset folder and referenced from the pattern

Since this was originally added to support the plugin in a docker environment (wp-env) that environment was used to verify that it is working as expected.

[vcanales]

Works as advertised; tested on localhost and with a local domain (wp.local)