How to reproduce:
1. Create a new HDRP template project
2. Click Window -> Render Pipeline -> HD Render Pipeline Wizard
3. Scroll to the bottom of the list and click "Upgrade Unity Builtin Scene Light Intensity for High Definition"
4. Observe the Scene view

Expected result: Light Intensity is increased only once
Actual result: Light Intensity can be increased multiple times

Reproducible with: 2019.3.0b4, 2019.3.1.f1, 2020.1.0a22
Could not test with: 2017.4.36f1, 2018.4.17f1, 2019.2.21f1, 2019.3.0b3(The setting in HDRP Wizard was not available)

Reproducible with package version: 7.1.1, 7.1.8, 8.0.0

Notes:
- CTRL-Z does not work to reduce the Intensity values
- Inspector window does not reflect the change in the lighting intensity
- "Upgrade Unity Builtin Scene Light Intensity for High Definition" became available in HDRP 7.1.1(2019.3.0b3)