qa: update kclient testing to RHEL 7.6

Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>

diff --git a/qa/cephfs/mount/kclient/overrides/distro/rhel/7.5.yaml b/qa/cephfs/mount/kclient/overrides/distro/rhel/7.5.yaml
deleted file mode 120000 (symlink)
index e2cdbd2..0000000
--- a/qa/cephfs/mount/kclient/overrides/distro/rhel/7.5.yaml
+++ /dev/null
@@ -1 +0,0 @@
-.qa/distros/supported-all-distro/rhel_7.5.yaml
\ No newline at end of file

diff --git a/qa/cephfs/mount/kclient/overrides/distro/rhel/rhel_7.6.yaml b/qa/cephfs/mount/kclient/overrides/distro/rhel/rhel_7.6.yaml
new file mode 120000 (symlink)
index 0000000..54ea19f
--- /dev/null
+++ b/qa/cephfs/mount/kclient/overrides/distro/rhel/rhel_7.6.yaml
@@ -0,0 +1 @@
+.qa/distros/all/rhel_7.6.yaml
\ No newline at end of file