query evaluation in get_service(s) omits lazy population of default traits

Here is one example to reproduce the bug:

```
from envisage.api import Application
from traits.api import Interface, provides, HasTraits, Str, Int, HasStrictTraits

class IPlumber(Interface):
""" What plumbers do! """

# The plumber's name.
name = Str

# The plumber's location.
location = Str

# The price per hour (in say, Estonian Krooni ;^)
price = Int

def fix_leaking_pipe(self, pipe):
""" Fix a leaking pipe! """

@provides(IPlumber)
class Plumber(HasTraits):
""" An actual plumber implementation! """

# The plumber's name.
name = Str

# The plumber's location.
location = Str

# The price per hour (in say, Estonian Krooni ;^)
price = Int

def fix_leaking_pipe(self, pipe):
""" Fix a leaking pipe! """
print('fixed!')

@provides(IPlumber)
class Foo(HasTraits):
foo = Int
price = Int(20)

if __name__ == '__main__':
application = Application()
fred = Plumber()
foo = Foo()
fred_id = application.register_service(IPlumber, fred)
foo_id = application.register_service(IPlumber, foo)

obj = application.get_services(IPlumber, 'price<30')

print(obj)
```

and the problematic code: https://github.com/enthought/envisage/blob/57338fcb0ea69c75bc3c86de18a5967d8e78c6c1/envisage/service_registry.py#L191-L198

Start with envisage/service_registry.py at the linked lines 191-198 and run the reproduction from the issue. Trace how get_services evaluates the `price<30` query before default Traits values are populated. Done means the query includes the Foo service with its default price, with the existing service lookup behavior preserved.

Written by the indexing model from the issue text.