ci: use smaller runners for CI pipelines (#2566)

CNCF has been nice to us to offer larger runners, but we need to be
careful not to abuse them.

Signed-off-by: Ramkumar Chinchani <rchincha@cisco.com>

.github/workflows/golangci-lint.yaml

@@ -13,7 +13,7 @@ permissions:
 jobs:
   golangci:
     name: lint
-    runs-on: ubuntu-latest-8-cores
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/setup-go@v5
         with:

.github/workflows/test.yaml

@@ -14,7 +14,7 @@ permissions: read-all
 jobs:
   test-run-minimal:
     name: Running zot without extensions tests
-    runs-on: ubuntu-latest-16-cores
+    runs-on: ubuntu-latest-4-cores
     steps:
       - uses: actions/checkout@v4
       - name: Install go
@@ -54,7 +54,7 @@ jobs:
       - uses: ./.github/actions/teardown-localstack
   test-run-extensions:
     name: Run zot with extensions tests
-    runs-on: ubuntu-latest-16-cores
+    runs-on: ubuntu-latest-4-cores
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-go@v5
@@ -93,7 +93,7 @@ jobs:
       - uses: ./.github/actions/teardown-localstack
   test-run-devmode:
     name: Running privileged tests on Linux
-    runs-on: ubuntu-latest-16-cores
+    runs-on: ubuntu-latest-4-cores
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-go@v5