Fix ThrowableProxy unit tests

Modified the regex patterns in RootCauseFirstThrowableProxyTest and
ExtendedThrowableProxyTest to find any packaging info in the throwable's
stack trace, including inexact matches.

On Cloudbees Jenkins, these tests were failing because they were looking
for an exact match of the JUnit package but only found an inexact one.

logback-classic/src/test/java/ch/qos/logback/classic/pattern/ExtendedThrowableProxyConverterTest.java

@@ -65,7 +65,7 @@ public void integration() {
     String res = pl.doLayout(e);
 
     // make sure that at least some package data was output
-    Pattern p = Pattern.compile(" \\[junit.*\\]");
+    Pattern p = Pattern.compile("\\s*at .*?\\[.*?\\]");
     Matcher m = p.matcher(res);
     int i = 0;
     while(m.find()) {

logback-classic/src/test/java/ch/qos/logback/classic/pattern/RootCauseFirstThrowableProxyConverterTest.java

@@ -19,6 +19,7 @@
 import ch.qos.logback.classic.PatternLayout;
 import ch.qos.logback.classic.spi.ILoggingEvent;
 import ch.qos.logback.classic.spi.LoggingEvent;
+
 import org.junit.Before;
 import org.junit.Test;
 
@@ -68,7 +69,7 @@ public void integration() {
 
     //then
     // make sure that at least some package data was output
-    Pattern p = Pattern.compile(" \\[junit.*\\]");
+    Pattern p = Pattern.compile("\\s*at .*?\\[.*?\\]");
     Matcher m = p.matcher(result);
     int i = 0;
     while(m.find()) {