fix holdout handling empty file paths.

[lechuga16]

An attempt is made to correct the following error

L 04/14/2025 - 00:03:03: [SM] Exception reported: String formatted incorrectly - parameter 3 (total 2)
L 04/14/2025 - 00:03:03: [SM] Blaming: optional/holdout_bonus.smx
L 04/14/2025 - 00:03:03: [SM] Call stack trace:
L 04/14/2025 - 00:03:03: [SM]   [0] VFormat
L 04/14/2025 - 00:03:03: [SM]   [1] Line 740, C:\Users\Sir\Documents\GitHub\L4D2-Competitive-Rework\addons\sourcemod\scripting\holdout_bonus.sp::PrintDebug
L 04/14/2025 - 00:03:03: [SM]   [2] Line 641, C:\Users\Sir\Documents\GitHub\L4D2-Competitive-Rework\addons\sourcemod\scripting\holdout_bonus.sp::KV_Load
L 04/14/2025 - 00:03:03: [SM]   [3] Line 182, C:\Users\Sir\Documents\GitHub\L4D2-Competitive-Rework\addons\sourcemod\scripting\holdout_bonus.sp::ConvarChange_KeyValuesPath
L 04/14/2025 - 00:03:03: [SM]   [5] ConVar.SetString
L 04/14/2025 - 00:03:03: [SM]   [6] Line 255, confoglcompmod\CvarSettings.sp::ClearAllSettings
L 04/14/2025 - 00:03:03: [SM]   [7] Line 114, confoglcompmod\CvarSettings.sp::CVS_ResetCvars_Cmd