Fixes #4169: $path configuration parameter adds terminating slash

[vga91]

Fixes #4169

The user probably had an unrelated problem with the issue,
as the 502 error should be a temporary bad gateway error.

In fact, the following command from curl, works both with and without the terminating slash.

curl  https://apoc-testing.openai.azure.com/openai/deployments/text-embedding-ada-002/embeddings/?api-version\=2023-07-01-preview\
  -H 'Content-Type: application/json' \
  -H 'api-key: <OPENAI_API_KEY>' \
  -d '{"input": ["Some Text"]}'

In any case, we made the change, as it is syntactically more correct, and to prevent potential errors that might occur in the future or with other non-OpenAI/Azure endpoints.

Anyway, we created a test case similar to the issue one.