Remove obselete entries and add "reduce obs space" option iasi filter

[emilyhcliu]

This PR proposes the following changes for IASI:

1. Remove obsolete entries related to QC flags in the observation filter
2. Rename mtiasi to iasi
3. Add `reduce obs space

There is a companion GDASApp PR #1292
This partly resolves Issue NOAA-EMC/GDASApp#1291

[emilyhcliu]

@danholdaway Thanks for reviewing this PR.

[emilyhcliu]

Test failed with the following message:platform linux -- Python 3.12.6, pytest-8.3.3, pluggy-1.5.0 -- /opt/hostedtoolcache/Python/3.12.6/x64/bin/python
cachedir: .pytest_cache
rootdir: /home/runner/work/jcb-gdas/jcb-gdas/jcb_repo
collecting ... collected 5 items

Error: The operation was canceled.

This does not look like a working test.
Can we merge this PR?