[Console] Show completed percentage, not a rounded value.

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

This pull request has 2 minor changes:
- 199/200 => 99% instead of 100% (there was no test case and I added one, everything else passes) In the past the value was rounded, the progress bar ended up being 100% for 0.5% of the total execution time. That means 18 seconds on a 1 hour process.
- Fixed the comments to match the inner workings of RedrawFrequency.

First Symfony PR and second overall so hope I just did this the right way.

PR #8419 Rebased for 2.2