ci: run CodeQL with build-mode none (#6045)

Autobuild compiled the whole test suite. The resulting database was so
large that the hosted runner repeatedly lost communication with the
server while importing the TRAP files (about 80 minutes in), which left
failed CodeQL analyses on develop and on pull requests. Analyze the
sources without building them instead.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

.github/workflows/codeql-analysis.yml

@@ -41,11 +41,10 @@ jobs:
       uses: github/codeql-action/init@9b3254085494b55a0f7c4c2b3d2d52cc712ce370 # v4.39.1
       with:
         languages: c-cpp
-
-    # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
-    # If this step fails, then you should remove it and run the build manually (see below)
-    - name: Autobuild
-      uses: github/codeql-action/autobuild@9b3254085494b55a0f7c4c2b3d2d52cc712ce370 # v4.39.1
+        # Analyze the sources without compiling them. Autobuild compiled the
+        # whole test suite and the resulting database was so large that the
+        # runner often lost communication with the server while importing it.
+        build-mode: none
 
     - name: Perform CodeQL Analysis
       uses: github/codeql-action/analyze@9b3254085494b55a0f7c4c2b3d2d52cc712ce370 # v4.39.1