Pull Request addon for PR #39453 .

Summary of Changes

With PR #39453, the two strings COM_MEDIA_FIELD_ILLEGAL_MIME_TYPES_DESC and COM_MEDIA_FIELD_ILLEGAL_MIME_TYPES_LABEL were deleted in the config and designated as deprecated in the administrator ini file.
The deprecated note is missing in the frontend language file.

This PR also adds the message in the frontend ini file.

Testing Instructions

code review

Actual result BEFORE applying this Pull Request

COM_MEDIA_FIELD_ILLEGAL_MIME_TYPES_DESC="A comma separated list of forbidden MIME types to upload."
COM_MEDIA_FIELD_ILLEGAL_MIME_TYPES_LABEL="Forbidden MIME Types"

Expected result AFTER applying this Pull Request

; Deprecated, will be removed with 5.0
COM_MEDIA_FIELD_ILLEGAL_MIME_TYPES_DESC="A comma separated list of forbidden MIME types to upload."
; Deprecated, will be removed with 5.0
COM_MEDIA_FIELD_ILLEGAL_MIME_TYPES_LABEL="Forbidden MIME Types"

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed