Fix build errors due to changes in warnings that VS 2022 17.1 produces. (#10621)
Disable warning about padding for abseil-cpp flat_hash_map.
Disable some warnings from compiling the test proto. This also required removing a line in CMakeList.txt where we move a level 4 warning to level 3. That ends up later on the command line and overrides the `/wd4800`. Couldn't find a way to handle that nicely. As we compile with `/W4` the value of moving 4800 to level 3 in dev mode is unclear so simplest was to remove that. Open to suggestions if there's a better way.