[BUG] parse of BUILD_INFO failed if not set

[vsantele]

Describe the bug
With a fresh environment on my computer, my flow raises an error with the tool promptflow_vectordb.tool.common_index_lookup.search.
The function _get_custom_dimensions inside promptflow_vectordb\tool\common_index_lookup.py cannot get a build_number because the environment variable BUILD_INFO is not set.

How To Reproduce the bug
Steps to reproduce the behavior, how frequent can you experience the bug:

1. Create a conda environment with python=3.11
2. Install the lastest version of promptflow (1.16.1), promptflow-tools (1.4.0) and promptflow-vectordb (0.2.13)
3. Create a flow using promptflow_vectordb.tool.common_index_lookup.search with a FAISS index from Azure ML (I didn't test with other options)
4. Run the flow

Expected behavior
The index lookup has to work without the BUILD_INFO. It has to have fallback build_number if the environment variable is not set.

Running Information(please complete the following information):

• Promptflow Package Version using pf -v:

{
  "promptflow": "1.16.1",
  "promptflow-azure": "1.16.1",
  "promptflow-core": "1.16.1",
  "promptflow-devkit": "1.16.1",
  "promptflow-tracing": "1.16.1"
}
promtflow-vectordb===0.2.13
promptflow-tools===1.4.0

• Operating System: Windows 11
• Python Version using python --version: python==3.11.10

Additional context
There are discussions at #3632 with this error, but it was not the main topic and the issue is closed.

[ferronsw]

The requirement of this ENV should be documented or made optional.
I've spend to many hours on finding this problem. I think many others with me.

[github-actions]

Hi, we're sending this friendly reminder because we haven't heard back from you in 30 days. We need more information about this issue to help address it. Please be sure to give us your input. If we don't hear back from you within 7 days of this comment, the issue will be automatically closed. Thank you!

[vsantele]

Up. What kind of information do you need?

[vsantele]

The source code of promptflow-vectordb is not available. So we cannot fix or make a PR for this.

Inside this repository, there is already a fix to fall back to a default value if BUILD_INFO is not set up.

promptflow/src/promptflow-core/promptflow/core/_serving/v1/app.py

Lines 134 to 139 in 40c84b4

	build_info = os.environ.get("BUILD_INFO", "")
	try:
	build_info_dict = json.loads(build_info)
	version = build_info_dict["build_number"]
	except Exception:
	version = __version__

The fix is very easy. Is there another way to ask for a fix?