Decrease the tempest build interval

Decreasing the build interval leads to faster state change detection,
so it will speed up the gating jobs.

It may increase the possibility of a "hidden" issues causes
indeterministic test results.

Change-Id: Ida5e7296e4ea53d761e0efef34376699337d8377
Correct InvalidInstanceID.NotFound test.

* exercises/euca.sh: The match filtering InvalidInstanceID.NotFound
is cleaned up to eliminate numerous leaning toothpicks, and now also
actually works. The previous version was incorporating literal
square brackets into the pattern where I think a character list
match may have been intended instead, but was not actually necessary
anyway.

Change-Id: I765a20000e7b6ba6deadce8cad3bbc9559fcdd0d
Merge "Correct InvalidInstanceID.NotFound test."
Merge "Decrease the tempest build interval"