qa/suites/rados/thrash-erasure-code-big: add k=4 m=2

Get better coverage for larger codes.

Signed-off-by: Sage Weil <sage@redhat.com>

diff --git a/qa/suites/rados/thrash-erasure-code-big/workloads/ec-rados-plugin=jerasure-k=4-m=2.yaml b/qa/suites/rados/thrash-erasure-code-big/workloads/ec-rados-plugin=jerasure-k=4-m=2.yaml
new file mode 120000 (symlink)
index 0000000..a4d836c
--- /dev/null
+++ b/qa/suites/rados/thrash-erasure-code-big/workloads/ec-rados-plugin=jerasure-k=4-m=2.yaml
@@ -0,0 +1 @@
+../../../../erasure-code/ec-rados-plugin=jerasure-k=4-m=2.yaml
\ No newline at end of file