make CI jobs testable without docker hub creds

Author: vszakats

.github/workflows/build_ci_multi.yml

@@ -25,6 +25,7 @@ jobs:
         install_latest: [true]
     steps:
       - name: "login docker hub"
+        if: ${{ secrets.DOCKER_HUB_USER }}
         env:
           DOCKER_HUB_USER: '${{ secrets.DOCKER_HUB_USER }}'
           DOCKER_HUB_TOKEN: '${{ secrets.DOCKER_HUB_TOKEN }}'

.github/workflows/build_latest_release_multi.yml

@@ -35,6 +35,7 @@ jobs:
           password: ${{ env.REGISTRY_PASSWORD }}
           registry: ${{ env.IMAGE_REGISTRY }}
       - name: "login docker hub"
+        if: ${{ secrets.DOCKER_HUB_USER }}
         env:
           DOCKER_HUB_USER: '${{ secrets.DOCKER_HUB_USER }}'
           DOCKER_HUB_TOKEN: '${{ secrets.DOCKER_HUB_TOKEN }}'

.github/workflows/build_master.yml

@@ -37,6 +37,7 @@ jobs:
           password: ${{ env.REGISTRY_PASSWORD }}
           registry: ${{ env.IMAGE_REGISTRY }}
       - name: "login docker hub"
+        if: ${{ secrets.DOCKER_HUB_USER }}
         env:
           DOCKER_HUB_USER: '${{ secrets.DOCKER_HUB_USER }}'
           DOCKER_HUB_TOKEN: '${{ secrets.DOCKER_HUB_TOKEN }}'

.github/workflows/build_master_dev.yml

@@ -38,6 +38,7 @@ jobs:
           password: ${{ env.REGISTRY_PASSWORD }}
           registry: ${{ env.IMAGE_REGISTRY }}
       - name: "login docker hub"
+        if: ${{ secrets.DOCKER_HUB_USER }}
         env:
           DOCKER_HUB_USER: '${{ secrets.DOCKER_HUB_USER }}'
           DOCKER_HUB_TOKEN: '${{ secrets.DOCKER_HUB_TOKEN }}'

.github/workflows/build_master_multi.yml

@@ -37,6 +37,7 @@ jobs:
           password: ${{ env.REGISTRY_PASSWORD }}
           registry: ${{ env.IMAGE_REGISTRY }}
       - name: "login docker hub"
+        if: ${{ secrets.DOCKER_HUB_USER }}
         env:
           DOCKER_HUB_USER: '${{ secrets.DOCKER_HUB_USER }}'
           DOCKER_HUB_TOKEN: '${{ secrets.DOCKER_HUB_TOKEN }}'