Set agent override version to 8.12.0.

Author: cmacknz

.buildkite/scripts/steps/integration_tests.sh

@@ -11,7 +11,7 @@ MAGE_SUBTARGET="${3:-""}"
 # Override the agent package version using a string with format <major>.<minor>.<patch>
 # NOTE: use only after version bump when the new version is not yet available, for example:
 # OVERRIDE_AGENT_PACKAGE_VERSION="8.10.3" otherwise OVERRIDE_AGENT_PACKAGE_VERSION="".
-OVERRIDE_AGENT_PACKAGE_VERSION=""
+OVERRIDE_AGENT_PACKAGE_VERSION="8.12.0"
 
 if [[ -n "$OVERRIDE_AGENT_PACKAGE_VERSION" ]]; then
   OVERRIDE_TEST_AGENT_VERSION=${OVERRIDE_AGENT_PACKAGE_VERSION}"-SNAPSHOT"