Reduce hostname length in tests and opcode py_compat count

This improves Issue 325 - new runtime and memory consumption is about
1/10 compared to before.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>

htest/Test/Ganeti/OpCodes.hs

@@ -438,7 +438,7 @@ case_AllDefined = do
 -- be skipped).
 case_py_compat :: HUnit.Assertion
 case_py_compat = do
-  let num_opcodes = length OpCodes.allOpIDs * 500
+  let num_opcodes = length OpCodes.allOpIDs * 100
   sample_opcodes <- sample' (vectorOf num_opcodes
                              (arbitrary::Gen OpCodes.OpCode))
   let opcodes = head sample_opcodes

htest/Test/Ganeti/TestCommon.hs

@@ -134,7 +134,7 @@ instance Show DNSChar where
 -- | Generates a single name component.
 genName :: Gen String
 genName = do
-  n <- choose (1, 64)
+  n <- choose (1, 16)
   dn <- vector n
   return (map dnsGetChar dn)