qa/suites/perf-basic: pin to 18.04

This will have same problems as https://tracker.ceph.com/issues/49139

trivial fix: removed ubuntu_latest having bionic as entry.

Signed-off-by: Neha Ojha <nojha@redhat.com>
(cherry picked from commit e5895dd8012f646ae9d67b9d1b331e7c06fe89d3)

diff --git a/qa/suites/perf-basic/ubuntu_18.04.yaml b/qa/suites/perf-basic/ubuntu_18.04.yaml
new file mode 120000 (symlink)
index 0000000..cfb85f1
--- /dev/null
+++ b/qa/suites/perf-basic/ubuntu_18.04.yaml
@@ -0,0 +1 @@
+.qa/distros/all/ubuntu_18.04.yaml
\ No newline at end of file

diff --git a/qa/suites/rados/cephadm/smoke/distro/ubuntu_latest.yaml b/qa/suites/rados/cephadm/smoke/distro/ubuntu_latest.yaml
deleted file mode 120000 (symlink)
index 3a09f9a..0000000
--- a/qa/suites/rados/cephadm/smoke/distro/ubuntu_latest.yaml
+++ /dev/null
@@ -1 +0,0 @@
-.qa/distros/supported/ubuntu_latest.yaml
\ No newline at end of file