How to reproduce:
1. Open the attached project("HDRP_Flicker")
2. Go to Scenes > SampleScene
3. Move around in the Scene View

Expected results: Scene view is not flickering
Actual result: Scene view is flickering

Reproducible with: 2019.1.11f1(HDRP 5.16.1), 2019.2.0b10(HDRP 6.9.0), 2019.3.0a10(HDRP 6.5.2)

Notes:
- Ambient Mode became available from 5.3.1
- First affected version in 2019.1 is 2019.1.0b2 as 5.3.1 package version was released on 2019-01-28 whereas the mentioned Unity version was released on 2019-01-30 and 2019.1.0b1 was released on 2019-01-23, thus, HDRP 5.3.1 became supported from 2019.1.0b2
- First affected version in 2019.2 is 2019.2.0a4 as it was released on 2019-01-31 whereas 2019.2.0a3 was released on 2019-01-24, thus, HDRP 5.3.1 became supported from 2019.2.0a4
- Camera with Render Texture should not include the object's layer with Volume where the Ambient Mode set to Dynamic in its Volume Layer Mask whereas the Main Camera has to include that layer in the Volume Layer Mask.
- Couldn't test 2019.2.0a4-2019.2.0a5 because of libcef crashes