sh: Fix some tests that used sh instead of ${SH}

so they tested the wrong sh.

This was caused because these tests were committed after the sh -> ${SH}
change but were created before.

tools/regression/bin/sh/errors/bad-keyword1.0

@@ -1,4 +1,4 @@
 # $FreeBSD$
 
-echo ':; fi' | sh -n 2>/dev/null && exit 1
+echo ':; fi' | ${SH} -n 2>/dev/null && exit 1
 exit 0

tools/regression/bin/sh/execution/func3.0

@@ -3,5 +3,5 @@
 # This may fail when parsing or when defining the function, or the definition
 # may silently do nothing. In no event may the function be executed.
 
-sh -c 'unset() { echo overriding function executed, bad; }; v=1; unset v; exit "${v-0}"' 2>/dev/null
+${SH} -c 'unset() { echo overriding function executed, bad; }; v=1; unset v; exit "${v-0}"' 2>/dev/null
 :