[v9_11] Configure with --enable-dnstap by default in GitLab CI
All platforms but OpenBSD have dnstap dependencies readily in their respective repositories, and dnstap thus can be tested there. Given that majority of images have dnstap dependencies available, it seems fitting to make dnstap enabled by default.
Also dnstap is disabled for TSAN jobs configured with --disable-atomic as it's known to produce TSAN errors (#2664) and for the gcc:noatomics job because it has threads disabled, which is a requirement for dnstap.
(cherry picked from commit deff0ae3)