qa/tests: replaced ubuntu_latest.yaml with ubuntu 20.04

resurrect 835f2f5f511e7363f4056e5137382982aac1bfbf, which was reverted by
1f885b6c2fdde1f3ab249a56f7b4b763556f4373

so all tests for `pacific` will be tested on the latest ubuntu version

Signed-off-by: Kefu Chai <kchai@redhat.com>
(cherry picked from commit 55564dbd01e6020a40d9a18d080aa7b1b9f86d5e)

diff --git a/qa/distros/supported-all-distro/ubuntu_latest.yaml b/qa/distros/supported-all-distro/ubuntu_latest.yaml
index 64a66d9aa487bdd4542cadd0ea9f16eb5598f36f..75d907e3b9cf89b29f9582831cfc1fa1ada69533 120000 (symlink)
--- a/qa/distros/supported-all-distro/ubuntu_latest.yaml
+++ b/qa/distros/supported-all-distro/ubuntu_latest.yaml
@@ -1 +1 @@
-../all/ubuntu_18.04.yaml
\ No newline at end of file
+../all/ubuntu_20.04.yaml
\ No newline at end of file

diff --git a/qa/distros/supported-random-distro$/ubuntu_latest.yaml b/qa/distros/supported-random-distro$/ubuntu_latest.yaml
index 64a66d9aa487bdd4542cadd0ea9f16eb5598f36f..75d907e3b9cf89b29f9582831cfc1fa1ada69533 120000 (symlink)
--- a/qa/distros/supported-random-distro$/ubuntu_latest.yaml
+++ b/qa/distros/supported-random-distro$/ubuntu_latest.yaml
@@ -1 +1 @@
-../all/ubuntu_18.04.yaml
\ No newline at end of file
+../all/ubuntu_20.04.yaml
\ No newline at end of file