CI: Remove the caching mechanism

After testing (everything works as excepted) and measuring the cache, we
noticed that the time improvement is not worth the additional
complexity. Hence, we decided to remove this cache but leave it in the
commit history in case it becomes relevant in the future.

This effectively reverts commit da11a13
"CI: Cache dependencies between runs".

Author: ibbem

.github/workflows/maven.yml

@@ -18,29 +18,7 @@ jobs:
     steps:
     - uses: actions/checkout@v4
     - uses: cachix/install-nix-action@v31
-    - name: List pre-installed store paths
-      run: find /nix/store -mindepth 1 -maxdepth 1 | sort > pre-installed
-    - uses: actions/cache/restore@v4
-      id: cache
-      with:
-        path: cache-closure.nar
-        key: nix-${{ hashFiles('.github/workflows/maven.yml', 'default.nix', 'nix/**', 'pom.xml', 'local-maven-repo') }}
-    - name: Import cache
-      if: steps.cache.outputs.cache-hit == 'true'
-      run: nix-store --import < cache-closure.nar
-    - name: Build dependency cache
-      if: steps.cache.outputs.cache-hit != 'true'
-      run: nix-build --out-link dependencies nix/github-workflow-dependencies.nix
-    - name: Export cache
-      if: steps.cache.outputs.cache-hit != 'true'
-      run: |
-        find /nix/store -mindepth 1 -maxdepth 1 | sort > store-paths
-        nix-store --export $(comm -13 pre-installed store-paths) > cache-closure.nar
-    - uses: actions/cache/save@v4
-      if: steps.cache.outputs.cache-hit != 'true'
-      with:
-        path: cache-closure.nar
-        key: nix-${{ hashFiles('.github/workflows/maven.yml', 'default.nix', 'nix/**', 'pom.xml', 'local-maven-repo') }}
+    # The dependencies could be cached if necessary. See PR #156 and da11a13c1451f5a52672fe494ac6e20116346865 for additional information.
     - name: Build
       run: nix-build
     - name: Upload Javadoc artifact