Remove Trusty testing

Opendev has dropped trusty from the mirrors.  With no testing the
distribution is effectively unsupported, add a release note.  Update a
few other random doc bits (that are not really that up to date
anyway).

Change-Id: I5bd0d0a94477cf8d84cef72f5d4b2e9e15ab9fd2

.zuul.d/jobs.yaml

@@ -24,7 +24,6 @@
         - centos-minimal/7-build-succeeds
         - centos-minimal/8-build-succeeds
         - pip-and-virtualenv/source-install-ubuntu
-        - ubuntu-minimal/trusty-build-succeeds
         - ubuntu-minimal/xenial-build-succeeds
         - ubuntu-minimal/bionic-build-succeeds
 
@@ -43,7 +42,6 @@
         - centos/8-build-succeeds
         - opensuse/build-succeeds
         - opensuse/opensuse15-build-succeeds
-        - ubuntu/trusty-build-succeeds
         - ubuntu/xenial-build-succeeds
         - ubuntu/bionic-build-succeeds
 

README.rst

@@ -12,7 +12,7 @@ the flexibility to customise the image build with their own elements.
 
 For example::
 
-  $ DIB_RELEASE=trusty disk-image-create -o ubuntu-trusty.qcow2 vm ubuntu
+  $ DIB_RELEASE=bionic disk-image-create -o ubuntu-bionic.qcow2 vm ubuntu
 
 will create a bootable Ubuntu Trusty based ``qcow2`` image.
 

doc/source/user_guide/supported_distros.rst

@@ -7,7 +7,6 @@ Distributions which are supported as a build host:
 - Debian 8 ("jessie")
 - Fedora 30, 31
 - RHEL 6, 7
-- Ubuntu 14.04 ("trusty")
 - Gentoo
 - openSUSE Leap 42.3, 15.0, 15.1 and Tumbleweed
 
@@ -18,6 +17,6 @@ Distributions which are supported as a target for an image:
 - Debian 8 ("jessie")
 - Fedora 30, 31
 - RHEL 6, 7
-- Ubuntu 12.04 ("precise"), 14.04 ("trusty")
+- 16.04 ("xenial"), 18.04 ("bionic")
 - Gentoo
 - openSUSE Leap 42.3, 15.0, 15.1 and Tumbleweed (opensuse-minimal only)

releasenotes/notes/trusty-testing-removal-51160ee59c5477d8.yaml

@@ -0,0 +1,5 @@
+---
+deprecations:
+  - Trusty testing has been removed; although we have not attempted to
+    disable support in elements, the distribution can be effectively
+    considered deprecated from this release.