chore: return main to the 2.x line and resume chart bumps

[charliedowler]

Why

Main uses a pre-release chart version, so the auto-bump bot cannot advance appVersion. The 2.x line has stopped shipping.

What changed

• Restore the stable values and templates from 2.16.6.
• Set the chart version to 2.16.7 and keep appVersion at 1.191.1.
• Remove the bump pause marker and regenerate the chart README.

3.0.0-beta.1 stays published. Its tag and release preserve the beta, so nothing is lost.

Verification

• The values and two template files match tag lightdash-2.16.6 byte for byte.
• The chart diff from lightdash-2.16.6 changes only version and appVersion.
• helm lint charts/lightdash passes.
• The default render contains no migration Job and uses /api/v1/health.
• The chart renders with image.tag=1.150.0.
• .chart-bump-paused does not exist.

Linear: SPK-1139