Eliminate need to get fingerprints during query execution time.

Why do fingerprinting at all during query execution time? The query analyzer already needs to get all fingerprints in question upfront for each AST node, so we can save fingerprint information in the AST nodes and then not deal with labels at all later.

This speeds up a 1h query for a single timeseries from 1.5s to 50ms. Also, less code! :)