(PUP-3248) Fix PMT tests for directory environment

The beaker host['distmoduledir'] variable is not meaningful if the
host is using directory environments (e.g. 'production').

This commit updates the helper methods for validating that a module
is (or is not) installed on the host by iterating over the
modulepath if a specific modulepath is not provided.

The calls to these helper methods have been updated for the change
in parameter ordering in the helper methods.
(PUP-3248) Use tmpdir for generating environments

This commit changes calls to the
generate_base_legacy_and_directory_environments helper to use a
tmpdir rather than master['puppetpath'] to isolate the test
environments and prevent collisions.

The generate_base_legacy_and_directory_environments has also been
altered to remove the `environmentpath` setting in the generated
configuration file.
Merge pull request #3109 from johnduarte/pmt_directory_env_support

(PUP-3248) Fix PMT tests for directory environment