chore: add more tests in middleware for code cov

[atheeshp]

Description

ref: #11087

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Author Checklist

All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.

I have...

• included the correct type prefix in the PR title
• added ! to the type prefix if API or client breaking change
• targeted the correct branch (see PR Targeting)
• provided a link to the relevant issue or specification
• followed the guidelines for building modules
• included the necessary unit and integration tests
• added a changelog entry to CHANGELOG.md
• included comments for documenting Go code
• updated the relevant documentation or specification
• reviewed "Files changed" and left comments if necessary
• confirmed all CI checks have passed

Reviewers Checklist

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your handle next to the items reviewed if you only reviewed selected items.

I have...

• confirmed the correct type prefix in the PR title
• confirmed ! in the type prefix if API or client breaking change
• confirmed all author checklist items have been addressed
• reviewed state machine logic
• reviewed API design and naming
• reviewed documentation is accurate
• reviewed tests and test coverage
• manually tested (if applicable)

[codecov]

Codecov Report

Merging #11694 (9e18dc7) into master (ddc23bc) will increase coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #11694      +/-   ##
==========================================
+ Coverage   65.87%   65.92%   +0.05%     
==========================================
  Files         667      667              
  Lines       70446    70446              
==========================================
+ Hits        46403    46442      +39     
+ Misses      21348    21306      -42     
- Partials     2695     2698       +3     

Impacted Files	Coverage Δ
x/group/keeper/keeper.go	53.78% <0.00%> (+0.42%)	⬆️
x/auth/middleware/sigverify.go	66.66% <0.00%> (+0.49%)	⬆️
x/auth/middleware/run_msgs.go	84.00% <0.00%> (+2.66%)	⬆️
x/auth/middleware/basic.go	70.29% <0.00%> (+6.43%)	⬆️
x/auth/middleware/fee.go	83.87% <0.00%> (+7.52%)	⬆️
x/auth/middleware/gas.go	93.75% <0.00%> (+16.66%)	⬆️
x/auth/middleware/tx.go	100.00% <0.00%> (+17.64%)	⬆️