Run trivy-cache job on ARM64 worker (#2925)

because we suspect this is the reason why later jobs that run on those
workers don't find the cache.

Might be related to:
https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cross-os-cache

Signed-off-by: Dimitris Karakasilis <dimitris@karakasilis.me>

.github/workflows/image-arm-pr.yaml

@@ -15,7 +15,7 @@ env:
 jobs:
   # Populate the trivy cache once for all later jobs to use
   trivy-cache:
-    runs-on: ubuntu-latest
+    runs-on: ARM64
     steps:
       - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4
         with:

.github/workflows/image-arm.yaml

@@ -83,7 +83,7 @@ jobs:
 
   # Populate the trivy cache once for all later jobs to use
   trivy-cache:
-    runs-on: ubuntu-latest
+    runs-on: ARM64
     steps:
       - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4
         with:

.github/workflows/release-arm.yaml

@@ -79,7 +79,7 @@ jobs:
 
   # Populate the trivy cache once for all later jobs to use
   trivy-cache:
-    runs-on: ubuntu-latest
+    runs-on: ARM64
     steps:
       - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4
         with: