[ios] Fixes ActivityIndicatorHeader subtitle cutoff

Changes the title and subtitle contentCompressionResistancePriority
to prevent them from being compressed by the stackView.

Bug: 862744
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I0587b639cb76215c7f1c5b3bc26fdf87a21ab7c3
Reviewed-on: https://chromium-review.googlesource.com/1157197
Commit-Queue: Sergio Collazos <sczs@chromium.org>
Reviewed-by: Kurt Horimoto <kkhorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579577}

ios/chrome/browser/ui/table_view/cells/table_view_activity_indicator_header_footer_item.mm

@@ -72,10 +72,16 @@
     self.titleLabel = [[UILabel alloc] init];
     self.titleLabel.font =
         [UIFont preferredFontForTextStyle:UIFontTextStyleHeadline];
+    [self.titleLabel
+        setContentCompressionResistancePriority:UILayoutPriorityRequired
+                                        forAxis:UILayoutConstraintAxisVertical];
     self.subtitleLabel = [[UILabel alloc] init];
     self.subtitleLabel.font =
         [UIFont preferredFontForTextStyle:UIFontTextStyleCaption1];
     self.subtitleLabel.textColor = [UIColor lightGrayColor];
+    [self.subtitleLabel
+        setContentCompressionResistancePriority:UILayoutPriorityRequired
+                                        forAxis:UILayoutConstraintAxisVertical];
 
     // Vertical StackView.
     UIStackView* verticalStack = [[UIStackView alloc]