assistant edit tool: Revert fuzzy matching (#26996)

#26935 is leading to bad edits, so let's revert it for now. I'll bring
back a version of this, but it'll likely just focus on indentation
instead of making the whole search fuzzy.

Release Notes: 

- N/A

Cargo.lock

@@ -718,7 +718,6 @@ dependencies = [
  "itertools 0.14.0",
  "language",
  "language_model",
- "pretty_assertions",
  "project",
  "rand 0.8.5",
  "release_channel",
@@ -728,7 +727,6 @@ dependencies = [
  "settings",
  "theme",
  "ui",
- "unindent",
  "util",
  "workspace",
  "worktree",