Avoid running build ARM image twice (#24858)
Avoid running build ARM image twice (#24858)

In case of "merge-run" (i.e. when maintainer merges somethin
to main or v2-*-test branch is pushed, the ARM instance does not
need to be built because in such case cache is built and pushed
for ARM image.
cfei18/incubator-airflow,apache/airflow,apache/airflow,nathanielvarona/airflow,apache/airflow,cfei18/incubator-airflow,nathanielvarona/airflow,cfei18/incubator-airflow,nathanielvarona/airflow,nathanielvarona/airflow,apache/airflow,apache/airflow,apache/airflow,nathanielvarona/airflow,nathanielvarona/airflow,cfei18/incubator-airflow,cfei18/incubator-airflow,cfei18/incubator-airflow