DO NOT MERGE: Timing test files
Checking how long every test file takes to run in the CI. In #26949 I'd like to run tests constraining that a whole file must be run in a single worker (so we can run `single` tests in parallel).

This means that files that will take a lot of time won't be parallelized well, and should be splitted for this to work. So, I want to know how long each takes.
Checking how long it takes every test file to see if some should be splitted for better parallelization I see this, which doesn't look right to me:
```
pandas/tests/io/test_html.py : 21m59.041s
pandas/tests/io/json/test_pandas.py : 8m50.339s
pandas/tests/io/parser/test_common.py : 6m45.860s
pandas/tests/io/excel/test_readers.py : 13m14.864s
```
Didn't check the files individually, I guess in some cases we want to test loading big files, but 22 minutes to test the html I/O sounds very exaggerated.

@pandas-dev/pandas-core is this expected? Did you try running that single file locally? No, wanted to check first that this is not expected and I'm missing something. If this doesn't seem right, I'll then try to figure out what's going on. The second one takes locally 4.6 seconds (and not almost 9 min). There are 2 out of 97 tests skipped (encoding related), of which one is an s3 test > pandas/tests/io/test_html.py

I'm seeing the two (not marked as slow) test_invalid_url tests as about 150s apiece. @datapythonista closable? Yep, let's close this for now, may need to reopen later to research on the timing problem, but I don't have time now.