Removing outdated STS code owners and adding one that was missing

Bug: 197237705
Test: code management CL. No expected test impact.
Change-Id: I17ec3a133f5a8f81260da34b6e6b842118bb6215
diff --git a/tests/tests/security/OWNERS b/tests/tests/security/OWNERS
index d0ad3ff..0db6ed8 100644
--- a/tests/tests/security/OWNERS
+++ b/tests/tests/security/OWNERS
@@ -2,7 +2,6 @@
 cbrubaker@google.com
 jeffv@google.com
 nnk@google.com
-mspector@google.com
-manjaepark@google.com
+musashi@google.com
 cdombroski@google.com
 hubers@google.com