Add restoring of cache from main and local branch in CI

Ref. eng/recordflux/RecordFlux#1737

.gitlab-ci.yml

@@ -42,9 +42,13 @@ workflow:
     key: $CI_JOB_NAME_SLUG-$CI_COMMIT_REF_SLUG-$SPARK_VERSION
     paths:
       - build/gnatprove_cache
-    fallback_keys:
-      - $CI_JOB_NAME_SLUG-main
-      - $CI_JOB_NAME_SLUG-main-$SPARK_VERSION
+    unprotect: true
+    when: always
+
+.spark-cache-main: &spark-cache-main
+    key: $CI_JOB_NAME_SLUG-main-$SPARK_VERSION
+    paths:
+      - build/gnatprove_cache
     unprotect: true
     when: always
 
@@ -455,6 +459,7 @@ verification_tests:
     - *setup_python
     - make prove_tests
   cache:
+    - *spark-cache-main
     - *spark-cache
 
 verification_python_tests:
@@ -477,6 +482,7 @@ verification_python_tests:
     - *setup_python
     - make prove_python_tests
   cache:
+    - *spark-cache-main
     - *spark-cache
 
 verification_apps:
@@ -505,6 +511,7 @@ verification_apps:
     - *setup_python
     - timeout -k 60 27600 make -C examples/apps/${APP} prove
   cache:
+    - *spark-cache-main
     - *spark-cache
 
 verification_documentation:
@@ -520,6 +527,7 @@ verification_documentation:
     - *setup_python
     - make prove_doc
   cache:
+    - *spark-cache-main
     - *spark-cache
 
 html_documentation: