Fix a bug where triggers would highlight lookahead matches. Only the first...

Fix a bug where triggers would highlight lookahead matches. Only the first range needs to be highlighted. That's the range of the string that matched the pattern. Additional ranges correspond to captures, not all of which are necessarily contained in the first range. Lookaheads fall outside the matched range and should not be highlihgted. Issue 5934.

sources/HighlightTrigger.m

@@ -427,14 +427,11 @@ enum {
                                 onString:(iTermStringLine *)stringLine
                     atAbsoluteLineNumber:(long long)lineNumber
                                     stop:(BOOL *)stop {
-    for (NSInteger i = 0; i < captureCount; i++) {
-        NSRange rangeInString = capturedRanges[i];
-        NSRange rangeInScreenChars = [stringLine rangeOfScreenCharsForRangeInString:rangeInString];
-        [[aSession screen] highlightTextInRange:rangeInScreenChars
-                      basedAtAbsoluteLineNumber:lineNumber
-                                         colors:[self colors]];
-    }
-
+    NSRange rangeInString = capturedRanges[0];
+    NSRange rangeInScreenChars = [stringLine rangeOfScreenCharsForRangeInString:rangeInString];
+    [[aSession screen] highlightTextInRange:rangeInScreenChars
+                  basedAtAbsoluteLineNumber:lineNumber
+                                     colors:[self colors]];
     return YES;
 }