[tools] testbot/orm: Let AddFilter() create the Collection Filter field.

[Francois Gouget]

All that initializing Filter in the constructor does is waste memory.
Documenting its existence there is enough.
Furthermore Clone() shouldn't have been setting it to an empty hashref.
Fortunately a typo made this ineffectual.

Signed-off-by: Francois Gouget 
---
 testbot/lib/ObjectModel/Collection.pm | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/testbot/lib/ObjectModel/Collection.pm b/testbot/lib/ObjectModel/Collection.pm
index bec5b1c5c..4e7a032a3 100644
--- a/testbot/lib/ObjectModel/Collection.pm
+++ b/testbot/lib/ObjectModel/Collection.pm
@@ -91,7 +91,7 @@ sub new($$$$$;$$@)
               MasterColNames      => $MasterColNames,
               MasterColValues     => $MasterColValues,
               MasterKey           => ComputeMasterKey($MasterColValues),
-              Filter              => undef,
+              # Filter => undef by default
               AllScopeItems       => $AllScopeItems || {},
               Items               => undef};
   if ($AllScopeItems)
@@ -136,7 +136,7 @@ sub Clone($)
               MasterColNames      => $self->{MasterColNames},
               MasterColValues     => $self->{MasterColValues},
               MasterKey           => $self->{MasterKey},
-              Filters             => {},
+              # Filter => undef by default
               AllScopeItems       => $self->{AllScopeItems},
               Items               => undef};
   # See Collection::new()