gh-91960: Remove Cirrus CI configuration (#113938)

Remove .cirrus.yml which was already disabled by being renamed to
.cirrus-DISABLED.yml. In total, Cirrus CI only run for less than one
month.

.cirrus-DISABLED.yml

@@ -1,29 +0,0 @@
-# gh-91960: Job disabled since Python is out of free credit (September 2023):
-# https://discuss.python.org/t/freebsd-gets-a-new-cirrus-ci-github-action-job-and-a-new-buildbot/33122/26
-
-freebsd_task:
-  freebsd_instance:
-    matrix:
-    - image: freebsd-13-2-release-amd64
-  # Turn off TCP and UDP blackhole.  It is not enabled by default in FreeBSD,
-  # but it is in the FreeBSD GCE images as used by Cirrus-CI.  It causes even
-  # local local connections to fail with ETIMEDOUT instead of ECONNREFUSED.
-  # For more information see https://reviews.freebsd.org/D41751 and
-  # https://github.com/cirruslabs/cirrus-ci-docs/issues/483.
-  sysctl_script:
-    - sysctl net.inet.tcp.blackhole=0
-    - sysctl net.inet.udp.blackhole=0
-  configure_script:
-    - mkdir build
-    - cd build
-    - ../configure --with-pydebug
-  build_script:
-    - cd build
-    - make -j$(sysctl -n hw.ncpu)
-  pythoninfo_script:
-    - cd build
-    - make pythoninfo
-  test_script:
-    - cd build
-    # dtrace fails to build on FreeBSD - see gh-73263
-    - make buildbottest TESTOPTS="-j0 -x test_dtrace --timeout=600"