optimize(main): implement more efficient way to get player count

[EinS4ckZwiebeln]

The old way to get the current player count was inefficient and over-complicated when such easy thing can be done in one line.
I don't think I have to explain any further why this solution is more reasonable in this scenario.

Questions (please complete the following information):

• Have you personally loaded this code into an updated qbcore project and checked all it's functionality? Yes
• Does your code fit the style guidelines? Yes
• Does your PR fit the contribution guidelines? Yes

[FBFezz]

Seems fine from my test on a localhost