Adding missing inits in tests to correct binding load errors

Description

Fixing the following UT errors

FAILED tests/unittests/test_dispatcher.py::TestThreadPoolSettingsPython37::test_dispatcher_sync_threadpool_set_worker - AssertionError: 0 != 1 : stack_trace: "  File \"/home/runner/work/azure-functions-python-worker/azure-functions-python-worker/azure_functions_worker/dispatcher.py\", line 399, in _handle__function_load_request\n    self._functions.add_function(\n  File \"/home/runner/work/azure-functions-python-worker/azure-functions-python-worker/azure_functions_worker/functions.py\", line 338, in add_function\n    input_types, output_types = self.validate_function_params(params,\n  File \"/home/runner/work/azure-functions-python-worker/azure-functions-python-worker/azure_functions_worker/functions.py\", line 228, in validate_function_params\n    raise FunctionLoadError(\n"
message: "FunctionLoadError: cannot load the show_context function: type of req binding in function.json \"httpTrigger\" does not match its Python annotation \"HttpRequest\""
FAILED tests/unittests/test_dispatcher.py::TestThreadPoolSettingsPython37::test_sync_invocation_request_log_threads - AssertionError: 0 != 1 : stack_trace: "  File \"/home/runner/work/azure-functions-python-worker/azure-functions-python-worker/azure_functions_worker/dispatcher.py\", line 399, in _handle__function_load_request\n    self._functions.add_function(\n  File \"/home/runner/work/azure-functions-python-worker/azure-functions-python-worker/azure_functions_worker/functions.py\", line 338, in add_function\n    input_types, output_types = self.validate_function_params(params,\n  File \"/home/runner/work/azure-functions-python-worker/azure-functions-python-worker/azure_functions_worker/functions.py\", line 228, in validate_function_params\n    raise FunctionLoadError(\n"
message: "FunctionLoadError: cannot load the show_context function: type of req binding in function.json \"httpTrigger\" does not match its Python annotation \"HttpRequest\""

Fixes #

PR information

[ ] The title of the PR is clear and informative.
[ ] There are a small number of commits, each of which has an informative message. This means that previously merged commits do not appear in the history of the PR. For information on cleaning up the commits in your pull request, see this page.
[ ] If applicable, the PR references the bug/issue that it fixes in the description.
[ ] New Unit tests were added for the changes made and CI is passing.

Quality of Code and Contribution Guidelines

[ ] I have read the contribution guidelines.

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (a86adb4) 85.51% compared to head (d90a732) 32.11%.

:exclamation: Current head d90a732 differs from pull request most recent head 94811c5. Consider uploading reports for the commit 94811c5 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #1354 +/- ## =========================================== - Coverage 85.51% 32.11% -53.41% =========================================== Files 34 34 Lines 1940 1940 Branches 367 366 -1 =========================================== - Hits 1659 623 -1036 - Misses 211 1316 +1105 + Partials 70 1 -69 ``` | [Flag](https://app.codecov.io/gh/Azure/azure-functions-python-worker/pull/1354/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Azure) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/Azure/azure-functions-python-worker/pull/1354/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Azure) | `32.11% <ø> (-53.36%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Azure#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

Azure / azure-functions-python-worker