Investigate .gitignore and .geminignore file support to ensure it is respected enough for file search and autocomplete #7330
Description
Failures to respect these files can result in memory bloat as directories uses wanted to ignore are included in their searches. In particular I believe file search is failing to fully respect these.
See #5485 for a full list of .gitignore and .geminiignore related issues. We do not need to solve all, just enough to mitigate memory issues.