Is it possible to change the default for in line previews so that the icon doesn't appear automatically when I upload and link to a file?
There is not a way to change the default. You may disable the inline preview on a case-by-case basis as described in How do I disable inline previews for files using the Rich Content Editor as an instructor?
There is some additional discussion in How do you disable the inline preview of a file? Unfortunately, you cannot apply the inline_disabled class to a parent element and have it apply to links in the children elements. For instance, you cannot wrap your entire page in a div with a class of inline_disabled and have it apply to all links on within that div element (the entire page).
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