Instrument Factories in Tests

[brianweir-da]

Currently in the Daml-Finance test suite, the tests create instruments directly thusly bypassing their related Factory. In order to make the tests closer to how the library is expected to be used, update the tests to use their related Factory instead.

[GeorgSchneider]

This only pertains to end-to-end tests, unit tests can (and should) take shortcuts. To be revisited as part of separating unit from e2e tests.

[markus-da]

Our current implementation to solve #753 requires the use of a factory in order to work (and be tested in the repo). I have changed it for the Callable Bond test, and the code did not get that much more complicated. It is also in a test util function, so the code is being reused for all callable bonds. @georg-da I would suggest changing this for the other dynamic instruments as well, what do you think?

[markus-da]

This has now been implemented for the dynamic instruments.

[matteolimberto-da]

This has now been implemented for all remaining instruments