[evm] Update Unstuck to Remove from Signer Cache

Resolves #1776 (closed). Posting for consideration, but leaving in draft for now. I wanted to take a pass at the implementation for my own understanding, but welcome thoughts from @Multipartite as you foresaw this issue before it occurred (which was unfortunately missed in the review rush) and have clearly thought it through more deeply. This will remain in draft until the new year as it was decided to delay 126 to avoid further rushed fixes.