Remove TxBuilder

[sahith-narahari]

Description

This PR removes TxBuilder of x/auth/types and it's usages
Ref : #6213

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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

[alexanderbez]

woohoo, I love code removal!

[codecov]

Codecov Report

Merging #6941 into master will increase coverage by 0.25%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #6941      +/-   ##
==========================================
+ Coverage   61.80%   62.06%   +0.25%     
==========================================
  Files         521      519       -2     
  Lines       32156    31954     -202     
==========================================
- Hits        19875    19833      -42     
+ Misses      10670    10511     -159     
+ Partials     1611     1610       -1     

[fedekunze]

utACK