Option to force Konflux Index

This is for periodic runs where we'll use the latest available Konflux
index. Periodic runs in CI have OPENSHIFT_CI variable set so we need to
have an option to force the Konflux index.

hack/lib/catalogsource.bash

@@ -23,9 +23,9 @@ function install_catalogsource {
 
   index_image="${INDEX_IMAGE}"
 
-  # Build bundle and index images only when running in CI or when DOCKER_REPO_OVERRIDE is defined.
-  # Otherwise the latest nightly build will be used for CatalogSource.
-  if [ -n "$OPENSHIFT_CI" ] || [ -n "$DOCKER_REPO_OVERRIDE" ]; then
+  # Build bundle and index images only when running in CI or when DOCKER_REPO_OVERRIDE is defined,
+  # unless overridden by FORCE_KONFLUX_INDEX.
+  if { [ -n "$OPENSHIFT_CI" ] || [ -n "$DOCKER_REPO_OVERRIDE" ]; } && [ -z "$FORCE_KONFLUX_INDEX" ]; then
     index_image=image-registry.openshift-image-registry.svc:5000/$OLM_NAMESPACE/serverless-index:latest
     rootdir="$(dirname "$(dirname "$(dirname "$(realpath "${BASH_SOURCE[0]}")")")")"