Update path of files to relative in error message for Replay mode conversation

[YauheniyaH]

Currently, when create Replay for chat with broken files ( deleted or incorrect format), error message contain absolute path to the file

Error message format can be following:

The following file attachments failed to process:

1. public/elephant.png: failed to download the attachment
2. public/business_tech_...ico: the attachment is not one of the supported types

or without public/ part

[VolhaBazhkova]

Fixed on staging, example,