fix: gain xp rate display with xp boost actived

[luanluciano93]

Description

This PR fixes the value shown on the xp gain rate display when the player has xp boost and an xp rate greater than 1.

Behaviour

If you change the rate to 10, and have the character's stamina bonus (x1.5), just buy an xp boost in the store, your xp gain rate shown will be 1575%, as the base will be 1000% + 50% of the stamina which will be 1500%, when using the boost it should add +50%, which would be 2250%.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Test Configuration:

• Server Version: Canary Main
• Client: 13.40
• Operating System: Windows 11

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code

[phacUFPE]

Could you please add into this PR the low level xp rate display fix? It is the getGrindingXpBoost.