mention easyblocks PR in gist when uploading test report for it + fix clean_gists.py script

[Flamefire]

Also enhance and fix the clean_gists script to not confuse easyconfigs and easyblocks repo which leads to deleting gists to keep

This is kinda crucial after the ability to create test reports for easyblocks PRs was introduced

An example of an upload after this is in: easybuilders/easybuild-easyblocks#2366 (comment)

[hound]

Some files could not be reviewed due to errors:

Traceback (most recent call last):

Traceback (most recent call last):
  File "/home/linters/.local/bin/flake8", line 5, in 
    from flake8.main.cli import main
ModuleNotFoundError: No module named 'flake8'

[hound]

Some files could not be reviewed due to errors:

Traceback (most recent call last):

Traceback (most recent call last):
  File "/home/linters/.local/bin/flake8", line 5, in 
    from flake8.main.cli import main
ModuleNotFoundError: No module named 'flake8'

[hound]

Some files could not be reviewed due to errors:

Traceback (most recent call last):

Traceback (most recent call last):
  File "/home/linters/.local/bin/flake8", line 5, in 
    from flake8.main.cli import main
ModuleNotFoundError: No module named 'flake8'

[hound]

Some files could not be reviewed due to errors:

Traceback (most recent call last):

Traceback (most recent call last):
  File "/home/linters/.local/bin/flake8", line 5, in 
    from flake8.main.cli import main
ModuleNotFoundError: No module named 'flake8'

[hound]

Some files could not be reviewed due to errors:

Traceback (most recent call last):

Traceback (most recent call last):
  File "/home/linters/.local/bin/flake8", line 5, in 
    from flake8.main.cli import main
ModuleNotFoundError: No module named 'flake8'

[hound]

Some files could not be reviewed due to errors:

Traceback (most recent call last):

Traceback (most recent call last):
  File "/home/linters/.local/bin/flake8", line 5, in 
    from flake8.main.cli import main
ModuleNotFoundError: No module named 'flake8'

[boegel]

lgtm