chore: update sqllogictest priority list with latest timing summary (8s --> 6s)

[alamb]

Which issue does this PR close?

• Follow-up to Add tests for sqllogictest prioritization #20656.

Rationale for this change

Make running sqllogictests faster by improving scheduling / parallelism

The sqllogictest runner runs test files in parallel but each file
sequentially, so it prioritizes known long-running files to run first to
minimize total wall-clock time. This list was last set in #20656.

The relative timings have since shifted. Running with the
--timing-summary flag now reports a different ordering of the longest
files, with nested_loop_join_spill.slt having become the longest by a
fair margin:

$ cargo test --profile=ci --test sqllogictests -- --timing-summary
Per-file elapsed summary (deterministic):
  1.    5.437s  nested_loop_join_spill.slt
  2.    3.471s  push_down_filter_regression.slt
  3.    3.458s  aggregate.slt
  4.    3.065s  joins.slt
  5.    2.852s  aggregate_skip_partial.slt
  6.    2.832s  imdb.slt
  7.    2.453s  window.slt
  8.    1.831s  group_by.slt
  9.    1.282s  clickbench.slt
 10.    1.055s  datetime/timestamps.slt
 11.    0.994s  array/array_has.slt
 12.    0.840s  cte.slt
 13.    0.748s  sort_pushdown.slt
 14.    0.714s  push_down_filter_parquet.slt
 15.    0.668s  projection_pushdown.slt

What changes are included in this PR?

• Update TEST_PRIORITY_ENTRIES to match the latest --timing-summary ordering
• Update the example output in the accompanying doc comment.

Are these changes tested?

There are some existing unit tests and I verified timings manually

cargo test --profile=ci --test sqllogictests

Main

Running with 16 test threads (available parallelism: 16)
Completed 475 test files in 8 seconds

This Branch

andrewlamb@Andrews-MacBook-Pro-3:~/Software/datafusion3$ cargo test --profile=ci --test sqllogictests
    Finished `ci` profile [unoptimized] target(s) in 0.53s
     Running bin/sqllogictests.rs (target/ci/deps/sqllogictests-0a94fbc565e8c132)
Running with 16 test threads (available parallelism: 16)
Completed 475 test files in 6 seconds

Are there any user-facing changes?

No.