Fix parameter validation order in condenser API functions

Move simple parameter validations (limit, truncate_body, permlink format)
before database lookups (account existence checks) to:
- Fail fast on invalid parameters without unnecessary DB queries
- Return expected error messages for negative tests
- Match test expectations for parameter validation errors

Fixed functions:
- extract_parameters_for_get_following_and_followers
- condenser_api_get_discussions_by_blog_or_feed
- condenser_api_get_discussion_by_author_before_date
- condenser_api_get_discussions_by_comments
- condenser_api_get_reblogged_by
- condenser_api_get_replies_by_last_update
- condenser_api_get_content

This resolves 35+ failing negative API tests that were expecting
parameter range errors but getting account existence errors instead.