Reduce log level of "unrecognized font family" from Error to Info

Summary:
Changelog:
[iOS][Fixed] - Unrecognized fontFamily values no longer trigger a redbox

## Context

We are starting to roll out a new consistent approach to style errors in React Native, where malformed or semantically invalid style values will never be treated as runtime errors. Instead, bad style values will consistently fall back to known defaults; the incorrect visual rendering will serve as the main runtime diagnostic for developers. We will advise developers to rely on static types for additional diagnostics.

This work will take place over multiple commits and possibly multiple releases of React Native.

## This diff

Here we fix this issue as it applies to the `fontFamily` style prop. The legacy (Paper) renderer on iOS is the only concrete implementation that had to change. Fabric and Android already implement the correct behaviour.

h/t EvanBacon for the report: https://twitter.com/Baconbrix/status/1623039650775371792

Reviewed By: huntie

Differential Revision: D43159284

fbshipit-source-id: 6afeef3abc5781e18671708f642073d25f2347e9

React/Views/RCTFont.mm

@@ -424,7 +424,7 @@ + (UIFont *)updateFont:(UIFont *)font
       isCondensed = isCondensedFont(font);
     } else {
       // Not a valid font or family
-      RCTLogError(@"Unrecognized font family '%@'", familyName);
+      RCTLogInfo(@"Unrecognized font family '%@'", familyName);
       if ([UIFont respondsToSelector:@selector(systemFontOfSize:weight:)]) {
         font = [UIFont systemFontOfSize:fontSize weight:fontWeight];
       } else if (fontWeight > UIFontWeightRegular) {

packages/rn-tester/js/examples/Text/TextExample.android.js

@@ -251,6 +251,9 @@ class TextExample extends React.Component<{...}> {
           <Text style={{fontFamily: 'monospace', fontWeight: 'bold'}}>
             Monospace Bold (After 5.0)
           </Text>
+          <Text style={{fontFamily: 'Unknown Font Family'}}>
+            Unknown Font Family
+          </Text>
         </RNTesterBlock>
         <RNTesterBlock title="Android Material Design fonts">
           <View style={{flexDirection: 'row', alignItems: 'flex-start'}}>

packages/rn-tester/js/examples/Text/TextExample.ios.js

@@ -639,6 +639,9 @@ exports.examples = [
             }}>
             Verdana bold
           </Text>
+          <Text style={{fontFamily: 'Unknown Font Family'}}>
+            Unknown Font Family
+          </Text>
         </View>
       );
     },