parquet: Refine time_elapsed_opening metric

[progval]

Is your feature request related to a problem or challenge?

For Parquet files, the time_elapsed_opening metric encompasses all of (in execution order):

1. Reading and parsing the footer/metadata (which is usually negligeable unless the page index is enabled, no metric either way)
2. Applying the row-level pushdown filter (pushdown_eval_time metric)
3. Parsing statistics and using them to prune (no metric)
4. Parsing Bloom Filters and using them to prune (no metric)
5. Pruning using the page filter (page_filter_eval_time metric)
6. Selecting columns and projecting (no metric, negligeable time)

Describe the solution you'd like

1. Add missing metrics:
   • metadata_load_time for part 1
   • statistics_eval_time for part 3
   • bloom_filter_eval_timefor part 4
2. Rename pushdown_eval_time to row_pushdown_eval_time, because statistics and eval time are also pushdown filters

Describe alternatives you've considered

Split statistics_eval_time and bloom_filter_eval_time each into two metrics, one for load time and one for eval time. But eval time is negligeable for both, so probably not worth it.

Additional context

No response