[chore] Fix more load test pipeline issues (open-telemetry#33885)

**Description:** <Describe what has changed.>
<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
This PR fixes more issues with the load test pipeline. Specifically, it
adjusts some things around artifact up/download which is needed as a
result of the breaking changes in GitHub Actions artifacts listed
[here](https://github.com/actions/upload-artifact#breaking-changes:~:text=Uploading%20to%20the%20same%20named,you%20will%20encounter%20an%20error.).
Also, it removes the issue generation step which seems far outdated as
it's failing with missing CircleCI env variables.

Also, I noticed that a few of the load tests fail consistently. To test.
the pipeline, I had to comment them out. Not sure, what to do with
them...

**Link to tracking Issue:**
Part of
open-telemetry#33577
Follow up to
open-telemetry#33860

**Testing:** Testing done on my personal fork. Link to working pipeline
run:
[Green run with some broken tests commented out, but pipeline
working](https://github.com/mowies/opentelemetry-collector-contrib/actions/runs/9789652148)
[Red run with broken
tests](https://github.com/mowies/opentelemetry-collector-contrib/actions/runs/9790395589)

**Documentation:** none added

---------

Signed-off-by: Moritz Wiesinger <moritz.wiesinger@dynatrace.com>

Author: mowies

.github/workflows/load-tests.yml

@@ -96,6 +96,7 @@ jobs:
         env:
           TEST_ARGS: "-test.run=${{ matrix.test }}"
       - name: Set results filename
+        if: ${{ failure() || success() }}
         id: filename
         run: echo "name=$(echo '${{ matrix.test }}' | sed -e 's/|/_/g')" >> $GITHUB_OUTPUT
       - name: Create Test Result Archive
@@ -107,18 +108,15 @@ jobs:
         continue-on-error: true
         uses: actions/upload-artifact@v4
         with:
+          name: test-result-archive-${{steps.filename.outputs.name}}
           path: ./*.tar
       - run: cp testbed/tests/results/benchmarks.json testbed/tests/results/${{steps.filename.outputs.name}}.json
       - name: Upload benchmarks.json
         uses: actions/upload-artifact@v4
         with:
-          name: benchmark-results
+          name: benchmark-results-${{steps.filename.outputs.name}}
           path: testbed/tests/results/${{steps.filename.outputs.name}}.json
 
-      - name: GitHub Issue Generator
-        if: ${{ failure() && github.ref == 'refs/heads/main' }}
-        run: ./.tools/issuegenerator $TEST_RESULTS
-
   update-benchmarks:
     runs-on: ubuntu-latest
     needs: [loadtest]
@@ -127,7 +125,8 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/download-artifact@v4
         with:
-          name: benchmark-results
+          pattern: benchmark-results-*
+          merge-multiple: true
           path: results
       - run: jq -s 'map(.[])' results/*.json > output.json
       - uses: benchmark-action/github-action-benchmark@v1