fix: Throttler token time calculation

[rumpfc]

Description
In one of my applications where I use Throttler I detected the getTokenTime() is already at the minimum of 1 seconds even if the token refresh rate is far from reached:

Example: 1 capacity, 3600 seconds -> After 10 minutes I expected 50 minutes to be left, but I was already at "1 second". Waiting another minute and executing the check, I was still at "1 second left".

This made me clear that the calculation for Throttler::getTokenTime() is still off, but the token value is calculated correctly after all, return false if $token < 1. This PR should fix that.

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[kenjis]

LGTM!

[MGatner]

Good sleuthing! Very cool test. Thanks for the PR!