refactor: minor changes follows #1348

[SukkaW]

Description:

The PR follows #1348 with a bugfix and a very slight performance improvement.

• Only enable package cache when the cache feature is available
  • In #1348 new package-manager-cache logic is not guarded by isCacheFeatureAvailable(), the PR fixes this.
• Don't read package.json if the previous version's cache config is used
  • We don't have to determine the package manager if the user has explicitly specified which package manager to use, which improves performance a little.

Related issue:

Check list:

• [ ] Mark if documentation changes are required.
• [ ] Mark if tests were added or updated to cover the changes.