qa: use position-independent link

Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>
(cherry picked from commit 1749edd668060d8453933c5dbfc779f27640043c)

diff --git a/qa/suites/rados/mgr/distro b/qa/suites/rados/mgr/distro
new file mode 120000 (symlink)
index 0000000..78f2991
--- /dev/null
+++ b/qa/suites/rados/mgr/distro
@@ -0,0 +1 @@
+.qa/distros/supported-random-distro$/
\ No newline at end of file

diff --git a/qa/suites/rados/mgr/supported-random-distro$ b/qa/suites/rados/mgr/supported-random-distro$
deleted file mode 120000 (symlink)
index 7cef21e..0000000
--- a/qa/suites/rados/mgr/supported-random-distro$
+++ /dev/null
@@ -1 +0,0 @@
-../basic/supported-random-distro$
\ No newline at end of file