[install] reenable again all workflows after debugging archiver.yml

Revert "[install] TEMPORARELY disable again all workflows but archiver.yml while debugging the latter (avoid overloading the CI)"
This reverts commit d4b10b9.

Author: valassi

.github/workflows/c-cpp.yml

@@ -3,8 +3,8 @@ name: C/C++ CI
 on:
   push:
     branches: [ master ]
-  #pull_request:
-  #  branches: [ master ]
+  pull_request:
+    branches: [ master ]
 
 jobs:
   debug_builds:

.github/workflows/testsuite_allprocesses.yml

@@ -15,8 +15,8 @@ on:
   workflow_dispatch:
 
   # Trigger the all-processes workflow for pull requests to master
-  #pull_request:
-  #  branches: [ master ]
+  pull_request:
+    branches: [ master ]
 
   # Trigger the all-processes workflow when new changes to the workflow are pushed
   # (NB: this is now disabled to avoid triggering two jobs when pushing to a branch for which a PR is opened)