disable logging to file in ci

Makefile

@@ -2,9 +2,9 @@ KEY_JAR=tools/key-2.11.0-exe.jar
 KEY_OVERFLOW_JAR=tools/key-2.11.0-o-exe.jar
 CI_TOOL=tools/citool-1.4.0-mini.jar
 
-checkCommand=java -Dkey.contractOrder="contract-order.txt" -cp "$(KEY_JAR):$(CI_TOOL)" de.uka.ilkd.key.CheckerKt --no-auto-mode --proof-path src/main/key
+checkCommand=java -Dlogback.configurationFile=./gradle/disablelogging.xml -Dkey.contractOrder="contract-order.txt" -cp "$(KEY_JAR):$(CI_TOOL)" de.uka.ilkd.key.CheckerKt --no-auto-mode --proof-path src/main/key
 
-checkOverflowCommand=java -Dkey.contractOrder="contract-order.txt" -cp "$(KEY_OVERFLOW_JAR):$(CI_TOOL)" de.uka.ilkd.key.CheckerKt -v --no-auto-mode --proof-path src/main/key-overflow
+checkOverflowCommand=java -Dlogback.configurationFile=./gradle/disablelogging.xml -Dkey.contractOrder="contract-order.txt" -cp "$(KEY_OVERFLOW_JAR):$(CI_TOOL)" de.uka.ilkd.key.CheckerKt -v --no-auto-mode --proof-path src/main/key-overflow
 
 default:
 	@echo Available targets:

gradle/disablelogging.xml

@@ -0,0 +1,16 @@
+<!-- -Dlogback.configurationFile=/path/to/config.xml -->
+<configuration>
+    <statusListener class="ch.qos.logback.core.status.NopStatusListener"/>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>[%date{HH:mm:ss.SSS}] %highlight(%-5level) %cyan(%logger{0}) - %msg%ex%n</pattern>
+        </encoder>
+        <filter class="ch.qos.logback.classic.filter.ThresholdFilter">
+            <level>ERROR</level>
+        </filter>
+    </appender>
+
+    <root level="error">
+        <appender-ref ref="STDOUT"/>
+    </root>
+</configuration>