Switch to ccache

sccache requires root access which fails when we use a docker, so move
to the simpler ccache which uses apt install.

.github/actions/do_build_ock_artefact/action.yml

@@ -26,7 +26,7 @@ runs:
           echo arch = ${{steps.calc_vars.outputs.arch}}
           echo toolchain = ${{steps.calc_vars.outputs.toolchain}}
 
-      # installs tools, ninja, installs llvm and sets up sccache
+      # installs tools, ninja, installs llvm and sets up ccache
       - name: setup
         uses:  ./.github/actions/setup_build
         with:

.github/actions/setup_build/action.yml

@@ -121,10 +121,12 @@ runs:
         fail-on-cache-miss: true
 
       # note the PR testing usage should set 'save' to false, to avoid PR testing creating new caches on a branch
-    - name: Setup sccache
+    - name: Setup ccache
       uses: hendrikmuhs/ccache-action@ed74d11c0b343532753ecead8a951bb09bb34bc9 # v1.2.14
       with:
         max-size: 200M
-        key: sccache-build
-        variant: sccache
+        key: ccache-build
+        variant: ccache
         save: ${{ inputs.save }}
+        append_timestamp: false
+

.github/workflows/create_publish_artifacts.yml

@@ -24,7 +24,7 @@ jobs:
       - name: Checkout repo
         uses: actions/checkout@v4
 
-       # installs tools, ninja, installs llvm and sets up sccache
+       # installs tools, ninja, installs llvm and sets up ccache
       - name: Setup ubuntu
         uses:  ./.github/actions/setup_build
         with: