bump guest ram to prevent kernel panics

one observation we had in down stream ci is
sometimes the cirros 0.6.2 image appared to
crash when using 128MB of ram.

upstream we have been dealing with semi random
kernel panics  which are losely corralated with
cinder volume usage.

Recently we optimisted the devstack jobs by using zswap
this has reduced memory pressure in the jobs.

This patch increase the ram allocated to a flavor
to see if we can afford that with the current conncurnace
level in an attempt to reduce kernel panics.

Two new parmaters are added to allow jobs or users
to set the desired ram size.
TEMPEST_FLAVOR_RAM=${TEMPEST_FLAVOR_RAM:-192}
TEMPEST_FLAVOR_ALT_RAM=${TEMPEST_FLAVOR_ALT_RAM:-256}

Change-Id: Ib6a2d5ab61a771d4f85bd2c2412052efadc77ac5

Author: SeanMooney

lib/tempest

@@ -102,6 +102,9 @@ TEMPEST_USE_TEST_ACCOUNTS=$(trueorfalse False TEMPEST_USE_TEST_ACCOUNTS)
 # it will run tempest with
 TEMPEST_CONCURRENCY=${TEMPEST_CONCURRENCY:-$(nproc)}
 
+TEMPEST_FLAVOR_RAM=${TEMPEST_FLAVOR_RAM:-192}
+TEMPEST_FLAVOR_ALT_RAM=${TEMPEST_FLAVOR_ALT_RAM:-256}
+
 # Functions
 # ---------
 
@@ -295,13 +298,15 @@ function configure_tempest {
             if [[ ! ( $available_flavors =~ 'm1.nano' ) ]]; then
                 # Determine the flavor disk size based on the image size.
                 disk=$(image_size_in_gib $image_uuid)
-                openstack --os-cloud devstack-admin flavor create --id 42 --ram 128 --disk $disk --vcpus 1 --property hw_rng:allowed=True m1.nano
+                ram=${TEMPEST_FLAVOR_RAM}
+                openstack --os-cloud devstack-admin flavor create --id 42 --ram ${ram} --disk $disk --vcpus 1 --property hw_rng:allowed=True m1.nano
             fi
             flavor_ref=42
             if [[ ! ( $available_flavors =~ 'm1.micro' ) ]]; then
                 # Determine the alt flavor disk size based on the alt image size.
                 disk=$(image_size_in_gib $image_uuid_alt)
-                openstack --os-cloud devstack-admin flavor create --id 84 --ram 192 --disk $disk --vcpus 1 --property hw_rng:allowed=True m1.micro
+                ram=${TEMPEST_FLAVOR_ALT_RAM}
+                openstack --os-cloud devstack-admin flavor create --id 84 --ram ${ram} --disk $disk --vcpus 1 --property hw_rng:allowed=True m1.micro
             fi
             flavor_ref_alt=84
         else