Don't use Bazel in build-manifests.sh

This is a partial revert of the commit

    e410cdd77968dae258e83ccc0171e855b8678063

which switches to using Bazel during manifests build. That in turn
does not work well during OBS build since Bazel tends to download
dependencies from the web.

diff --git a/hack/build-manifests.sh b/hack/build-manifests.sh
index 79b8676b8..6add64769 100755
--- a/hack/build-manifests.sh
+++ b/hack/build-manifests.sh
@@ -33,20 +33,15 @@ kubevirt_logo_path="assets/kubevirt_logo.png"
 rm -rf ${MANIFESTS_OUT_DIR}
 rm -rf ${MANIFEST_TEMPLATES_OUT_DIR}
 
-rm -rf "${TESTS_OUT_DIR}/tools"
-mkdir -p "${TESTS_OUT_DIR}/tools"
-templator=${TESTS_OUT_DIR}/tools/manifest-templator
-
-bazel run \
-    --config=${ARCHITECTURE} \
-    //:build-manifest-templator -- ${templator}
+(cd ${KUBEVIRT_DIR}/tools/manifest-templator/ && go_build)
 
 # first process file includes only
 args=$(cd ${KUBEVIRT_DIR}/manifests && find . -type f -name "*.yaml.in" -not -path "./generated/*")
 for arg in $args; do
     infile=${KUBEVIRT_DIR}/manifests/${arg}
     outfile=${KUBEVIRT_DIR}/manifests/${arg}.tmp
-    ${templator} \
+
+    ${KUBEVIRT_DIR}/tools/manifest-templator/manifest-templator \
         --process-files \
         --generated-manifests-dir=${KUBEVIRT_DIR}/manifests/generated/ \
         --input-file=${infile} >${outfile}
@@ -75,7 +70,7 @@ for arg in $args; do
     outfile=${final_out_dir}/${manifest}
     template_outfile=${final_templates_out_dir}/${manifest}.j2
 
-    ${templator} \
+    ${KUBEVIRT_DIR}/tools/manifest-templator/manifest-templator \
         --process-vars \
         --namespace=${namespace} \
         --cdi-namespace=${cdi_namespace} \
@@ -103,7 +98,7 @@ for arg in $args; do
         continue
     fi
 
-    ${templator} \
+    ${KUBEVIRT_DIR}/tools/manifest-templator/manifest-templator \
         --process-vars \
         --namespace="{{ namespace }}" \
         --cdi-namespace="{{ cdi_namespace }}" \