ibc : replace strings.Contains to bytes.Contains

[PrathyushaLakkireddy]

Description

closes: #8539

---

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer
• Review Codecov Report in the comment section below once CI passes

[codecov]

Codecov Report

Merging #8574 (8166f87) into master (591e46f) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #8574   +/-   ##
=======================================
  Coverage   61.39%   61.40%           
=======================================
  Files         656      656           
  Lines       37320    37336   +16     
=======================================
+ Hits        22914    22927   +13     
- Misses      12005    12007    +2     
- Partials     2401     2402    +1     

Impacted Files	Coverage Δ
x/ibc/core/02-client/keeper/grpc_query.go	76.47% <100.00%> (ø)
x/staking/keeper/validator.go	80.48% <0.00%> (-0.04%)	⬇️
x/staking/keeper/keeper.go	58.06% <0.00%> (+1.39%)	⬆️

[fedekunze]

thanks!