Append/update builtins deprecations warnings instead of prepend

[Taragolis]

Fix bug in test warning capture system introduced in #38905
There is redefine DeprecationWarning, PendingDeprecationWarning which are ignored by default in Python, however the problem that it use Prepend/Insert

# From CaptureWarningsPlugin
00 = {tuple: 5} ('always', None, <class 'PendingDeprecationWarning'>, None, 0)
01 = {tuple: 5} ('always', None, <class 'DeprecationWarning'>, None, 0)
# Explicit set as pytest.mark.filterwarnings
02 = {tuple: 5} ('default', None, <class 'airflow.exceptions.RemovedInAirflow3Warning'>, None, 0)
# Implicit set during pytest collect
03 = {tuple: 5} ('error', None, <class 'airflow.exceptions.RemovedInAirflow3Warning'>, None, 0)
04 = {tuple: 5} ('error', None, <class 'airflow.utils.context.AirflowContextDeprecationWarning'>, None, 0)
05 = {tuple: 5} ('error', None, <class 'airflow.exceptions.AirflowProviderDeprecationWarning'>, None, 0)
...

As result error might not happen if airflow.exceptions.RemovedInAirflow3Warning raisedduring test run because it subclass of DeprecationWarning and in this case rule 'always', None, <class 'DeprecationWarning'>, None, 0 will choose instead of 'error', None, <class 'airflow.exceptions.RemovedInAirflow3Warning'>, None, 0

After changes it update already existed and defined values in warnings.filters

# Explicit set as pytest.mark.filterwarnings
00 = {tuple: 5} ('default', None, <class 'airflow.exceptions.RemovedInAirflow3Warning'>, None, 0)
# Implicit set during pytest collect
01 = {tuple: 5} ('error', None, <class 'airflow.exceptions.RemovedInAirflow3Warning'>, None, 0)
02 = {tuple: 5} ('error', None, <class 'airflow.utils.context.AirflowContextDeprecationWarning'>, None, 0)
03 = {tuple: 5} ('error', None, <class 'airflow.exceptions.AirflowProviderDeprecationWarning'>, None, 0)
...
# Updated from CaptureWarningsPlugin
19 = {tuple: 5} ('always', None, <class 'PendingDeprecationWarning'>, None, 0)
20 = {tuple: 5} ('always', None, <class 'DeprecationWarning'>, None, 0)
...

---

^ Add meaningful description above
Read the Pull Request Guidelines for more information.
In case of fundamental code changes, an Airflow Improvement Proposal (AIP) is needed.
In case of a new dependency, check compliance with the ASF 3rd Party License Policy.
In case of backwards incompatible changes please leave a note in a newsfragment file, named {pr_number}.significant.rst or {issue_number}.significant.rst, in newsfragments.