Make system tests output filenames more descriptive (#776)

Rename `stdout.log` to `system-tests-stdout.log` and `stderr.log` to `system-tests-stderr.log`.

Author: MakisH

tools/tests/README.md

@@ -36,7 +36,7 @@ Workflow for the preCICE v3 release testing:
 
 6. Download the build artifacts from Summary > runs.
 
-    - In there, you may want to check the `stdout.log` and `stderr.log` files.
+    - In there, you may want to check the `system-tests-stdout.log` and `system-tests-stderr.log` files.
     - The produced results are in `precice-exports/`, the reference results in `reference-results-unpacked`.
     - Compare using, e.g., ParaView or [fieldcompare](https://gitlab.com/dglaeser/fieldcompare): `fieldcompare dir precice-exports/ reference/`. The `--diff` option will give you `precice-exports/diff_*.vtu` files, while you can also try different tolerances with `-rtol` and `-atol`.
 

tools/tests/systemtests/Systemtest.py

@@ -117,7 +117,7 @@ def _get_length_of_name(results: List[SystemtestResult]) -> int:
         with open(os.environ["GITHUB_STEP_SUMMARY"], "a") as f:
             print("\n\n", file=f)
             print(
-                "In case a test fails, download the archive from the bottom of this page and look into each `stdout.log` and `stderr.log`. The time spent in each step might already give useful hints.",
+                "In case a test fails, download the archive from the bottom of this page and look into each `system-tests-stdout.log` and `system-tests-stderr.log`. The time spent in each step might already give useful hints.",
                 file=f)
             print(
                 "See the [documentation](https://precice.org/dev-docs-system-tests.html#understanding-what-went-wrong).",
@@ -543,9 +543,9 @@ def __repr__(self):
         return f"{self.tutorial.name} {self.case_combination}"
 
     def __write_logs(self, stdout_data: List[str], stderr_data: List[str]):
-        with open(self.system_test_dir / "stdout.log", 'w') as stdout_file:
+        with open(self.system_test_dir / "system-tests-stdout.log", 'w') as stdout_file:
             stdout_file.write("\n".join(stdout_data))
-        with open(self.system_test_dir / "stderr.log", 'w') as stderr_file:
+        with open(self.system_test_dir / "system-tests-stderr.log", 'w') as stderr_file:
             stderr_file.write("\n".join(stderr_data))
 
     def __apply_max_time_override(self):