chore: Unify build configuration script into one

Earlier ci/meson-build.sh and ci/ci-build.sh.
The latter we then renamed to the more descriptive build-configuration-matrix.sh.

Both scripts are doing the same thing but for different build systems.
So lets merge them together.

Signed-off-by: Michael Vetter <jubalh@iodoru.org>

.github/workflows/main.yml

@@ -36,13 +36,13 @@ jobs:
             buildsystem: meson
             tests: unit
             omemo: signal
-            script: ./ci/ci-meson-build.sh
+            script: ./scripts/build-configuration-matrix.sh meson
             omemo_env: libsignal
           - flavor: debian
             buildsystem: meson
             tests: unit
             omemo: libomemo
-            script: ./ci/ci-meson-build.sh
+            script: ./scripts/build-configuration-matrix.sh meson
             omemo_env: libomemo-c
 
     name: ${{ matrix.flavor }} | ${{ matrix.buildsystem }} | ${{ matrix.tests }} | ${{ matrix.omemo }}