chore: increase cpu usage safety threshold to 90%

This is a temporary measure for running an upscaling comparison.

The commit will be reverted.

ant-node/src/bin/antnode/main.rs

@@ -418,7 +418,7 @@ You can check your reward balance by running:
         use rand::{thread_rng, Rng};
 
         const CPU_CHECK_INTERVAL: Duration = Duration::from_secs(60);
-        const CPU_USAGE_THRESHOLD: f32 = 50.0;
+        const CPU_USAGE_THRESHOLD: f32 = 90.0;
         const HIGH_CPU_CONSECUTIVE_LIMIT: u8 = 5;
         const NODE_STOP_DELAY: Duration = Duration::from_secs(1);
         const INITIAL_DELAY_MIN_S: u64 = 10;