All reports of unnecessary-testsuite-autopkgtest-field for the archive. The extended description of this tag is:
You do not need to specify a Testsuite: autopkgtest field if a debian/tests/control file exists. It is automatically added by dpkg-source(1) since dpkg 1.17.1.
Please remove this line from your debian/control file.
This tag has not been emitted in any package tested by Lintian.