chore: bump pip in nodejs_mono_repo Dockerfile

[parthea]

This PR removes pip older than 26 in the nodejs_mono_repo Dockerfile to address CVE-2026-1703 and CVE-2025-8869

root@54c11bcacc81:/synthtool# find / -name "pip-*" 2>/dev/null 
/opt/venv/synthtool/lib/python3.13/site-packages/pip-26.0.1.dist-info
/opt/venv/synthtool/bin/pip-install-dependency-groups
/root/.pyenv/test/pip-rehash.bats
/root/.pyenv/pyenv.d/exec/pip-rehash
/root/.pyenv/pyenv.d/exec/pip-rehash.bash
/root/.pyenv/versions/3.13.12/lib/python3.13/site-packages/pip-26.0.1.dist-info

Towards b/483202433
Towards b/483409870

[parthea]

This is ready for review but not merge