CI: Include a job index in names of collected artifacts

And include "extra" Linux elements to further disambiguate
archive names.

The current naming of artifacts is inadequate when it comes
to files whose differing name-parts only come from array
values, as arrays are not automatically converted to string.
For example, both artifacts for failing "socketserver" and
"no_x11" CI jobs will claim the same name, and whichever job
finishes last is allowed to overwrite another matching name
artifact.

Reference:
https://docs.github.com/en/actions/reference/workflows-and-actions/expressions#functions

closes: #18556

Signed-off-by: Aliaksei Budavei <0x000c70@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

.github/actions/test_artifacts/action.yml

@@ -3,11 +3,39 @@ description: "Upload failed test artifacts"
 runs:
   using: "composite"
   steps:
+    - name: Collect matrix properties for naming
+      uses: actions/github-script@v8
+      id: matrix-props
+      env:
+        MATRIX_PROPS: ${{ toJSON(matrix) }}
+      with:
+        # An array-flattening-to-string JavaScript function.
+        script: |
+          const f = function (x) { return x.toString().length > 0; }
+          const g = function (x) {
+            return (Array.isArray(x))
+              ? x.filter(f)
+                .map((function (h) { return function (y) { return h(y); }; })(g))
+                .join('-')
+              : x;
+          }
+          return Object.values(JSON.parse(process.env.MATRIX_PROPS))
+            .filter(f)
+            .map(g)
+            .join('-');
+        # By default, the JSON-encoded return value of the function is
+        # set as the "result".
+        result-encoding: string
     - name: Upload failed tests
       uses: actions/upload-artifact@v4
       with:
         # Name of the artifact to upload.
-        name: GH-${{ github.run_id }}-${{ github.run_attempt }}-${{ github.job }}-${{ join(matrix.*, '-') }}-failed-tests
+        name: ${{ format('GH-{0}-{1}-{2}-{3}-{4}-failed-tests',
+          github.run_id,
+          github.run_attempt,
+          github.job,
+          strategy.job-index,
+          steps.matrix-props.outputs.result) }}
 
         # A file, directory or wildcard pattern that describes what
         # to upload.