Poll database fewer times
Remove superflous pgrep check
Split upgrade logic into separate Upgrader package.
Refactor logger into separate package.

[#78655542]
Correct order of package and version files in runner.go

[#78655542]
Correctly stop standalone MySQL node.

[#78655542]
Added tests to cover failure cases for starting/stopping DB during upgrade.

- Refactored code

[#78655542]
Remove unnecessary initializer arguments.

[#78655542]
Increase polling delay to 10 seconds.

[#78655542]