docs: drop stale tracebloc-helm-charts references in INSTALL.md

[saadqbal]

`docs/INSTALL.md:203,220,229` still mention `tracebloc-helm-charts` as an alternative repo where the chart might be developed. That repo was renamed to `tracebloc/client` and the chart now lives solely here. The references mislead operators into thinking there's a parallel repo to look at.

The "Publishing the chart (maintainers)" section is the only place where these stale names appear. Trimming them is a few-line edit.

Acceptance criteria

• No remaining `tracebloc-helm-charts` references in `docs/INSTALL.md`.
• Maintainer publishing instructions stay correct for the current single-repo setup.