Tune Conda CI timeout and other minor improvements

[carmocca]

What does this PR do?

• Fixes script to pin versions
• Adds a per-test timeout of 2.5 minutes. We should avoid relying on the GitHub timeout, as they just kill the job and we miss out on the hanging stack trace.
• Removes randomization of tests

Does your PR introduce any breaking changes? If yes, please list them.

None

Before submitting

• [n/a] Was this discussed/approved via a GitHub issue? (not for typos and docs)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure your PR does only one thing, instead of bundling different changes together?
• [n/a] Did you make sure to update the documentation with your changes? (if necessary)
• [n/a] Did you write any new necessary tests? (not for typos and docs)
• Did you verify new and existing tests pass locally with your changes?
• Did you list all the breaking changes introduced by this pull request?
• [n/a] Did you update the CHANGELOG? (not for typos, docs, test updates, or internal minor changes/refactorings)

PR review

• Is this pull request ready for review? (if not, please submit in draft mode)
• Check that all items from Before submitting are resolved
• Make sure the title is self-explanatory and the description concisely explains the PR
• Add labels and milestones (and optionally projects) to the PR so it can be classified

cc @carmocca @akihironitta @Borda

[github-actions]

Build Error! No Linked Issue found. Please link an issue or mention it in the body using #<issue_id>

[github-actions]

Build Error! No Linked Issue found. Please link an issue or mention it in the body using #<issue_id>

[codecov]

Codecov Report

Merging #10769 (698eee1) into master (49d09aa) will decrease coverage by 0%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #10769   +/-   ##
=======================================
- Coverage      90%      90%   -0%     
=======================================
  Files         177      177           
  Lines       16491    16491           
=======================================
- Hits        14910    14907    -3     
- Misses       1581     1584    +3