Wrong assumption in `_post_process_reports` discards output to terminal

When running with --html, the processing removes printing the fixtures teardown log to the terminal.

It comes from a wrong assumption that the last report status is valid for all.
https://github.com/pytest-dev/pytest-html/blob/fdcd5c6331861c338e12537313b395300007f42e/src/pytest_html/html_report.py#L279-L282
And, as the plugin modifies the test_report object it has side-effects on other users like _pytest.terminal.py.
https://github.com/pytest-dev/pytest-html/blob/fdcd5c6331861c338e12537313b395300007f42e/src/pytest_html/html_report.py#L308-L310

Testing

Example test file:

import pytest


@pytest.fixture
def config():
    print('SETUP')
    yield
    print('TEARDOWN')


def test_example(config):
    print('CALL')
    assert 0

Expected output

In a normal execution, I would get the output:

python3 -m pytest --tb=short test_file.py 
======================== test session starts ========================
platform linux -- Python 3.8.10, pytest-6.2.5, py-1.11.0, pluggy-1.0.0
rootdir: /home/gha/tmp/test_pytest_html
plugins: html-3.1.1, metadata-1.11.0
collected 1 item                                                    

test_file.py F                                                [100%]

============================= FAILURES ==============================
___________________________ test_example ____________________________
test_file.py:13: in test_example
    assert 0
E   assert 0
----------------------- Captured stdout setup -----------------------
SETUP
----------------------- Captured stdout call ------------------------
CALL
--------------------- Captured stdout teardown ----------------------
TEARDOWN
====================== short test summary info ======================
FAILED test_file.py::test_example - assert 0
========================= 1 failed in 0.01s =========================

Real output

When running with --html it would remove the TEARDOWN output.

python3 -m pytest --tb=short --html=/tmp/out.html test_file.py 
======================== test session starts ========================
platform linux -- Python 3.8.10, pytest-6.2.5, py-1.11.0, pluggy-1.0.0
rootdir: /home/gha/tmp/test_pytest_html
plugins: html-3.1.1, metadata-1.11.0
collected 1 item                                                    

test_file.py F                                                [100%]

============================= FAILURES ==============================
___________________________ test_example ____________________________
test_file.py:13: in test_example
    assert 0
E   assert 0
----------------------- Captured stdout setup -----------------------
SETUP
----------------------- Captured stdout call ------------------------
CALL
------------- generated html file: file:///tmp/out.html -------------
====================== short test summary info ======================
FAILED test_file.py::test_example - assert 0
========================= 1 failed in 0.02s =========================

--- out	2022-01-19 18:04:21.025161810 +0100
+++ out_html	2022-01-19 18:04:15.325074196 +0100
@@ -15,8 +15,7 @@
 SETUP
 ----------------------------- Captured stdout call -----------------------------
 CALL
---------------------------- Captured stdout teardown ---------------------------
-TEARDOWN
+------------------ generated html file: file:///tmp/out.html -------------------
 =========================== short test summary info ============================
 FAILED test_file.py::test_example - assert 0
-============================== 1 failed in 0.01s ===============================
+============================== 1 failed in 0.02s ===============================

Debugging

By adding a some print in the plugin.py file (still on the version from pypi locally).

    def _post_process_reports(self):
        for test_name, test_reports in self.reports.items():
            import pprint
            print()
            pprint.pprint(test_reports)

It would show that, at least, "outcome" should not be taken from the last one.

python3 -m pytest --tb=short --html=/tmp/out.html test_file.py  
=========================== test session starts ============================
platform linux -- Python 3.8.10, pytest-6.2.5, py-1.11.0, pluggy-1.0.0
rootdir: /home/gha/tmp/test_pytest_html
plugins: html-3.1.1, metadata-1.11.0
collected 1 item                                                           

test_file.py F                                                       [100%]
[<TestReport 'test_file.py::test_example' when='setup' outcome='passed'>,
 <TestReport 'test_file.py::test_example' when='call' outcome='failed'>,
 <TestReport 'test_file.py::test_example' when='teardown' outcome='passed'>]


================================= FAILURES =================================
_______________________________ test_example _______________________________
test_file.py:13: in test_example
    assert 0
E   assert 0
-------------------------- Captured stdout setup ---------------------------
SETUP
--------------------------- Captured stdout call ---------------------------
CALL
---------------- generated html file: file:///tmp/out.html -----------------
========================= short test summary info ==========================
FAILED test_file.py::test_example - assert 0
============================ 1 failed in 0.02s =============================

Possible fix

When removing the overwriting on test_report.outcome and test_report.when I would get again TEARDOWN in the output.
Not checked the html output with this.

pytest-html could create a new combined test_report object instead of modifying the one given by pytest to be sure that even if this is needed, it would not change the rest of the world behavior.

I tried adding a copy before modifying test_report and it fixes the terminal output.
https://github.com/pytest-dev/pytest-html/blob/fdcd5c6331861c338e12537313b395300007f42e/src/pytest_html/html_report.py#L305-L309

             # outcome on the right comes from the outcome of the various
             #  test_reports that make up this test case
             #    we are just carrying it over to the final report.
+            import copy
+            test_report = copy.copy(test_report)
             test_report.outcome = report_outcome
             test_report.when = "call"

Start at src/pytest_html/html_report.py, especially the _post_process_reports logic around the linked lines, and reproduce the issue with the provided fixture and test_example case using pytest --tb=short --html=.... Confirm that terminal output retains Captured stdout teardown while the HTML report still works without changing pytest's original report object for other consumers.