Remove migrate_langs from tools/signing/nightly/update-responses-base-config.yml

While looking at generated .htaccess for update_responses for nightly, I noticed we still have migrate_langs in tools/signing/nightly/update-responses-base-config.yml, which is not needed since we only have the ALL bundle now.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information