tests: disable shallow narrow tests with simple store

I think these are failing because of issues with flags processing
in the simple store. Let's revisit this later.

Differential Revision: https://phab.mercurial-scm.org/D3103

tests/test-narrow-shallow-merges.t

@@ -1,3 +1,5 b''
+#require no-reposimplestore
+
   $ . "$TESTDIR/narrow-library.sh"
 
 create full repo

tests/test-narrow-shallow.t

@@ -1,3 +1,5 b''
+#require no-reposimplestore
+
   $ . "$TESTDIR/narrow-library.sh"
 
   $ hg init master