test(langchain): Separate test to remove conditional (#6076)

Split out cases of `test_langchain_openai_tools_agent` with sensitive `gen_ai.*` attributes suppressed to a new `test_langchain_openai_tools_agent_no_prompts` test. Remove per-case conditionals that branch on `send_default_pii` and `include_prompts`.

Author: alexander-alderman-webb