chg: ci: Raise respdiff third-party and recent-named disagreement thresholds

The third-party comparison is right at the 0.4 % threshold, making it
fail quite often. The current range of observed values ranges from
0.3-0.5 %. Raise the threshold to 0.5 %.

The recent-named comparison produces values ranging from 0.05 to 0.12 %,
but appears to be more sensitive to time of the day when the test runs.
Raise the threshold to 0.15 %.

Both results are stable within the specified ranges across the last
three releases in both main and bind-9.20 series.

Merge branch 'nicki/respdiff-threshold-bump' into 'main'

See merge request isc-projects/bind9!12286