PMM-14305 Fix ClickHouse dirty migration state

[ademidoff]

PMM-14305

Link to the Feature Build: SUBMODULES-4070

PR Summary
This pull request features the following changes:

• improvements to database migration error handling
• a partial migration from the deprecated github.com/pkg/errors package to the standard library errors package
• clarification of logger context usage.

Error handling improvements:

• Replaced usage of github.com/pkg/errors with the Go standard library errors package in both db.go and main.go, simplifying dependencies and modernizing error handling. [1] [2] [3] [4]

Database migration robustness:

• Enhanced the runMigrations function in db.go to handle dirty migration states: if a migration fails and leaves the database dirty, it now attempts to force the migration version and re-run migrations, improving reliability during upgrades.

Logger context API clarification:

• Updated documentation for Get in logger.go to clarify that SetEntry (not Set) must be called before retrieving a logger from context.
• Removed the unused Set function from logger.go, streamlining the logger context API to only use SetEntry.

[ademidoff]

This was unused.