x/upgrade gRPC query service

[amaury1093]

Description

ref: #5921

---

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 #6590 into master will increase coverage by 1.50%.
The diff coverage is 66.12%.

@@            Coverage Diff             @@
##           master    #6590      +/-   ##
==========================================
+ Coverage   55.60%   57.10%   +1.50%     
==========================================
  Files         457      484      +27     
  Lines       27440    29145    +1705     
==========================================
+ Hits        15257    16644    +1387     
- Misses      11083    11313     +230     
- Partials     1100     1188      +88     

[aaronc]

Left a few documentation comments. Otherwise LGTM. Good work! 🎉

[anilcse]

ACK 🎉