Fix dir issues in comparing images

[forsyth2]

Issue resolution

• Closes [Bug]: Errors in 2024-10-25 test of main #635

Select one: This pull request is...

• a bug fix: increment the patch version
• a small improvement: increment the minor version
• an incompatible (non-backwards compatible) API change: increment the major version

1. Does this do what we want it to do?

Objectives:

• Fix bug in integration testing where image_check_failures directories weren't generating properly.
• The other issues of [Bug]: Errors in 2024-10-25 test of main #635 will be resolved elsewhere:
  • Per [Bug]: Errors in 2024-10-25 test of main #635 (comment), the lnd issue will be resolved by Update to diags handling #633.
  • The image check failures that show up are consistent with the changes from Fixing African easterly wave density plots in TC analysis e3sm_diags#851. We can update the expected results accordingly, but I'm hesitant to do that until we get Update to diags handling #633 merged to correct the lnd issue. So, I will do that after Update to diags handling #633 merges.

Required:

• Product Management: I have confirmed with the stakeholders that the objectives above are correct and complete.
• Testing: I have added or modified at least one "min-case" configuration file to test this change. Every objective above is represented in at least one cfg.
• This is specifically part of weekly testing.
• Testing: I have considered likely and/or severe edge cases and have included them in testing.

2. Are the implementation details accurate & efficient?

Required:

• Logic: I have visually inspected the entire pull request myself.
• Logic: I have left GitHub comments highlighting important pieces of code logic. I have had these code blocks reviewed by at least one other team member.

3. Is this well documented?

Required:

• Documentation: by looking at the docs, a new user could easily understand the functionality introduced by this pull request.
• This is non-user facing.

4. Is this code clean?

Required:

• Readability: The code is as simple as possible and well-commented, such that a new team member could understand what's happening.
• Pre-commit checks: All the pre-commits checks have passed.