ZTS: Temporarily disable several upgrade tests

[behlendorf]

Motivation and Context

Keep the CI green while a known issue is being worked. This change
will be reverted once the failures have been addressed.

Description

Until issues #9185 and #9186 have been resolved the following zpool
upgrade tests are being disabled to prevent CI failures.

zpool_upgrade_002_pos,
zpool_upgrade_003_pos,
zpool_upgrade_004_pos,
zpool_upgrade_007_pos,
zpool_upgrade_008_pos

How Has This Been Tested?

Locally disabled, pending confirmation from a full CI run.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the ZFS on Linux code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• All commit messages are properly formatted and contain Signed-off-by.

[codecov]

Codecov Report

Merging #9225 into master will increase coverage by 0.38%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #9225      +/-   ##
==========================================
+ Coverage   79.24%   79.63%   +0.38%     
==========================================
  Files         400      279     -121     
  Lines      122012    81187   -40825     
==========================================
- Hits        96687    64650   -32037     
+ Misses      25325    16537    -8788

Flag	Coverage Δ
#kernel	79.63% <ø> (-0.17%)	⬇️
#user	?

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e6203d2...02491fd. Read the comment docs.