fix: unnecessary imports

[faddat]

• removed the independent go.mod files from db
• removed independent go.mod and go.sum from groups module
• Solves unnecessary import issues and removes go.mod and go.sum from groups and db

Description

Closes: #10742

Removes independent go.mod and go.sum from db and groups, purges unnecessary imports.

cosmos/gaia#1099

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[faddat]

Seems the build system expects these modules to have their own go.mod and go.sum

generally speaking, and for ergonomics with the majority of code editing suites (goland, vscode) you want exactly one of each of go.mod and go.sum, so I'd suggest that we fix the build system, not make it harder to work on the cosmos-sdk.

[tac0turtle]

why are you removing the go.mods from db and groups? this was done on purpose.

[tac0turtle]

multiple go.mods is on purpose. lets not remove them

[faddat]

I'll revise.

This should really be treated more like an exploration of the issue, and represented my first set of guesses.