ci: bump go and remove buildjet

[julienrbrt]

Description

• Bumps go in CI to latest version
• Reverts chore: Buildjet pr #12231 (We will speed up CI with Investigate how to speedup SDK chain build times #12805)
• Add slack notification on Cosmos SDK release

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Leaving this at draft first, so we can compare the actual run time.

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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

All items are required. Please add a note if the item is not applicable and please add
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 #13674 (274d907) into main (6b4db20) will decrease coverage by 0.10%.
The diff coverage is 100.00%.

❗ Current head 274d907 differs from pull request most recent head bb9b9bc. Consider uploading reports for the commit bb9b9bc to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #13674      +/-   ##
==========================================
- Coverage   54.80%   54.69%   -0.11%     
==========================================
  Files         647      657      +10     
  Lines       55794    57158    +1364     
==========================================
+ Hits        30579    31265     +686     
- Misses      22724    23362     +638     
- Partials     2491     2531      +40     

Impacted Files	Coverage Δ
simapp/app.go	77.84% <ø> (ø)
client/tx/factory.go	29.21% <100.00%> (+0.80%)	⬆️
simapp/genesis.go	100.00% <0.00%> (ø)
simapp/simd/cmd/testnet.go	61.98% <0.00%> (ø)
simapp/simd/cmd/genaccounts.go	89.09% <0.00%> (ø)
simapp/export.go	11.94% <0.00%> (ø)
simapp/state.go	0.00% <0.00%> (ø)
simapp/test_helpers.go	30.25% <0.00%> (ø)
simapp/simd/cmd/root.go	70.23% <0.00%> (ø)
... and 3 more

[julienrbrt]

The Slack notification didn't work for 0.46.4 because I didn't backport this 😢