ci: stop scanning test/ directory with dependabot

[nancysangani]

Closes #5253

The pip ecosystem entry with directory: "/" would scan any requirements files found under test/, generating false positive
alerts for packages that are only used as test fixtures for the vulnerability scanner itself — they are never installed or run.

Add an ignore block with a paths filter to exclude everything under test/** from dependabot's pip scanning, while keeping dependabot active for the actual project dependencies.

[Copilot]

Pull request overview

Updates Dependabot configuration to prevent pip dependency scanning from flagging test-fixture requirement files under test/, reducing false-positive vulnerability alerts while keeping Dependabot enabled for real project dependencies.

Changes:

• Removes previously commented-out ecosystem entries intended to suppress /test/ scanning.
• Adds an ignore rule to the pip update configuration intended to exclude test/**.

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[Copilot]

The new ignore rule uses dependency-name: "*" with a paths: filter. Dependabot's ignore entries are evaluated by dependency name/version/update-type; if paths is not a supported key (and gets ignored), this will effectively ignore all pip dependency updates for the repo, disabling the intended weekly pip updates. Please verify Dependabot supports paths here; if not, a safer approach is to scope the pip update directory to only the folder(s) containing real project manifests, or rename/move the test fixture requirement files so they are not detected as pip manifests.

Suggested change

	ignore:
	- dependency-name: "*"
	paths:
	- "test/**"