qa/suites/perf-basic: only test on bionic

because centos8/rhel8 does not package collectl or pdsh anymore. but
these packages are required by CBT for collecting performance stats.
so instead of testing on all supported distros, let's run the perf tests
only on distros offering these packages.

Signed-off-by: Kefu Chai <kchai@redhat.com>

diff --git a/qa/suites/perf-basic/distros/.qa b/qa/suites/perf-basic/distros/.qa
new file mode 120000 (symlink)
index 0000000..fea2489
--- /dev/null
+++ b/qa/suites/perf-basic/distros/.qa
@@ -0,0 +1 @@
+../.qa
\ No newline at end of file

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