[9.18] fix: ci: Set more lenient respdiff limits

After !9950, respdiff's maximal disagreement percentage needs to be
adjusted as target disagreements between the tested version of the
"main" branch and the reference one jumped for the respdiff,
respdiff:asan, and respdiff:tsan jobs from on average 0.07% to 0.16% and
from 0.12% to 0.17% for the respdiff-third-party job.

In !9950, we concluded setting MAX_DISAGREEMENTS_PERCENTAGE to double
the average disagreement percentage works fine in the CI.

(cherry picked from commit 9acc0c8543b6173c35019982bd6677a421204bff)

Backport of MR !10293

Merge branch 'backport-mnowak/more-lenient-respdiff-limits-9.18' into 'bind-9.18'

See merge request isc-projects/bind9!10848