ci: remove librarian skipping on matrix builds (#3969)

It doesn't work due to
https://github.com/orgs/community/discussions/9141.

Author: meltsufin

.github/workflows/ci.yaml

@@ -18,8 +18,6 @@ jobs:
           should_run:
             - '!internal/librariangen/**'
   build:
-    needs: changes
-    if: needs.changes.outputs.should_run == 'true'
     runs-on: ubuntu-22.04
     strategy:
       matrix:
@@ -332,8 +330,6 @@ jobs:
             --batch-mode \
             --no-transfer-progress
   showcase:
-    needs: changes
-    if: needs.changes.outputs.should_run == 'true'
     runs-on: ubuntu-22.04
     strategy:
       matrix: