Add extra to disable ripple in STL demo

This Cl adds an extra that will be used by performance tests to disable
the ripple, as they currently have a negative impact on Tangor tests
(see b/203141462#comment14 for details).

Bug: 291071158
Test: Manual, started the app with the extra enabled
Flag: EXEMPT test app
Change-Id: Ia19c8cdc6097a96dd1d903cf07d4588669c37dbb
1 file changed