[UT] Remove potentially buggy SQL test case for mem_pool property of resource groups (backport #66104)

[mergify]

Why I'm doing:

I recently added E2E SQL test cases for testing the mem_pool property.

• [UT] Add SQL tests for mem_pool property of resource groups #65859

One of the test cases has an incorrect regex.

show verbose resource groups all;
-- result:
[REGEX][^shared_resource_group_for_brad]
-- !result

The intention was to assert that the expression cannot be matched in the result.
It instead tries to match a single character that is not present in the brackets.
The correct regex should use a negative lookahead to implement the intended behavior.

The test case, however, does not fail, as the result coincidentally does not start with any of these characters.

What I'm doing:

The check is actually redundant, as we already assert that the resource group was not created in the previous check.
Instead of adding another complicated regex with negative lookaheads, I am simply removing it.

Fixes #issue

What type of PR is this:

• BugFix
• Feature
• Enhancement
• Refactor
• UT
• Doc
• Tool

Does this PR entail a change in behavior?

• Yes, this PR will result in a change in behavior.
• No, this PR will not result in a change in behavior.

If yes, please specify the type of change:

• Interface/UI changes: syntax, type conversion, expression evaluation, display information
• Parameter changes: default values, similar parameters but with different default values
• Policy changes: use new policy to replace old one, functionality automatically enabled
• Feature removed
• Miscellaneous: upgrade & downgrade compatibility, etc.

Checklist:

• I have added test cases for my bug fix or my new feature
• This pr needs user documentation (for new or modified features or behaviors)
  • I have added documentation for my new feature or new function
• This is a backport pr

Bugfix cherry-pick branch check:

• I have checked the version labels which the pr will be auto-backported to the target branch
  • 4.0
  • 3.5
  • 3.4
  • 3.3

---

Note

Removes an incorrect regex-based assertion and a duplicate show verbose resource groups all call from the mem_pool resource group test.

• Tests (SQL mem_pool resource groups):
  • Remove invalid regex assertion block from R/test_create_two_resource_groups_with_mem_pool_different_mem_limit that attempted to verify absence in show verbose resource groups all output.
  • Simplify T/test_create_two_resource_groups_with_mem_pool_different_mem_limit by removing a duplicate show verbose resource groups all call, leaving a single invocation.

^{Written by Cursor Bugbot for commit eef6213. This will update automatically on new commits. Configure here.}

---

This is an automatic backport of pull request #66104 done by [Mergify](https://mergify.com).

[mergify]

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[chelseaw0]

ignore merge 4.0.3