chore: remove unused dependencies

Remove 30 dependencies across 18 packages that have no imports in
source code and are not peer dependencies of any other dependency.

Signed-off-by: Fredrik Adelöw <freben@spotify.com>
Made-with: Cursor

packages/techdocs-cli/package.json

@@ -51,7 +51,6 @@
     "@backstage/plugin-techdocs-node": "workspace:^",
     "commander": "^14.0.3",
     "fs-extra": "^11.0.0",
-    "global-agent": "^3.0.0",
     "http-proxy": "^1.18.1",
     "react-dev-utils": "^12.0.0-next.60",
     "serve-handler": "^6.1.3",