[`ruff`] reintroduce `demisto/content` to `ruff-ecosystem` (#27305)
## Summary
Reintroducing `demisto/content` back to `ruff-ecosystem`, it's a huge
repo with 4.5K py file and 2.5M loc, so may have catch some cases for
ecosystem report. It was previously commented out in
https://github.com/astral-sh/ruff/pull/12129 due to the use of removed
`E999`
Issue with the use of removed rules upstream is resolved, though
apparently `E999` was dropped from selection a while ago and new issue
with the use of removed `UP038` occurred, but it's resolved now too -
https://github.com/demisto/content/pull/45227
Syntax error in still present in
https://github.com/demisto/content/blob/master/Packs/ThreatQ/Integrations/ThreatQ/ThreatQ.py,
so keeping `exclude`. Though apparently it doesn't break
`ruff-ecosystem` anymore, but keeping it safe for now. I've submitted a
fix upstream https://github.com/demisto/content/pull/45275, so `exclude`
can be removed later too.
## Test Plan
Tested running `ruff-ecosystem` locally, no issues found.