Disable SX126X_RX_BOOSTED_GAIN for Heltec v4

It causes RX overload and bad RX sensitivity. We should let the LNA
handle the gain.

Author: weebl2000

variants/heltec_v4/platformio.ini

@@ -27,7 +27,7 @@ build_flags =
   -D PIN_VEXT_EN_ACTIVE=HIGH
   -D LORA_TX_POWER=10 ;If it is configured as 10 here, the final output will be 22 dbm.
   -D MAX_LORA_TX_POWER=22 ; Max SX1262 output
-  -D SX126X_DIO2_AS_RF_SWITCH=true
+  -D SX126X_DIO2_AS_RF_SWITCH=false
   -D SX126X_DIO3_TCXO_VOLTAGE=1.8
   -D SX126X_CURRENT_LIMIT=140
   -D SX126X_RX_BOOSTED_GAIN=1