fix: install uv inside active venv

[jamesgao-jpg]

Summary

• Fix scripts/install_deps.sh so uv is installed into the active virtualenv when VIRTUAL_ENV is set.
• Keep the existing pip3 install --user uv path for non-virtualenv installs.
• PR Update build scripts #1619 introduced the uv bootstrap path; this adjusts it for Jenkins jobs that already put a venv first in PATH.

Test Plan

• Reproduced the old failure with a temporary virtualenv and no pre-existing uv on PATH.
• Verified the virtualenv path installs and resolves uv from the temp venv.
• Verified the non-virtualenv path still installs and resolves uv from the Python user bin.
• bash -n scripts/install_deps.sh
• git diff --check origin/main..origin/tmp_knowhere_python_ver_fix

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[mergify]

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