test: remove unnecessary timezone America/Chicago

It is wrong to change the timezone only to setTestNow().
Remnants of the old code? Now UTC is the default timezone.

Author: kenjis

tests/system/I18n/TimeLegacyTest.php

@@ -419,31 +419,31 @@ public function testAgeNow(): void
 
     public function testAgeFuture(): void
     {
-        TimeLegacy::setTestNow('June 20, 2022', 'America/Chicago');
+        TimeLegacy::setTestNow('June 20, 2022');
         $time = TimeLegacy::parse('August 12, 2116 4:15:23pm');
 
         $this->assertSame(0, $time->getAge());
     }
 
     public function testGetAgeSameDayOfBirthday(): void
     {
-        TimeLegacy::setTestNow('December 31, 2022', 'America/Chicago');
+        TimeLegacy::setTestNow('December 31, 2022');
         $time = TimeLegacy::parse('December 31, 2020');
 
         $this->assertSame(2, $time->getAge());
     }
 
     public function testGetAgeNextDayOfBirthday(): void
     {
-        TimeLegacy::setTestNow('January 1, 2022', 'America/Chicago');
+        TimeLegacy::setTestNow('January 1, 2022');
         $time = TimeLegacy::parse('December 31, 2020');
 
         $this->assertSame(1, $time->getAge());
     }
 
     public function testGetAgeBeforeDayOfBirthday(): void
     {
-        TimeLegacy::setTestNow('December 30, 2021', 'America/Chicago');
+        TimeLegacy::setTestNow('December 30, 2021');
         $time = TimeLegacy::parse('December 31, 2020');
 
         $this->assertSame(0, $time->getAge());

tests/system/I18n/TimeTest.php

@@ -426,31 +426,31 @@ public function testAgeNow(): void
 
     public function testAgeFuture(): void
     {
-        Time::setTestNow('June 20, 2022', 'America/Chicago');
+        Time::setTestNow('June 20, 2022');
         $time = Time::parse('August 12, 2116 4:15:23pm');
 
         $this->assertSame(0, $time->getAge());
     }
 
     public function testGetAgeSameDayOfBirthday(): void
     {
-        Time::setTestNow('December 31, 2022', 'America/Chicago');
+        Time::setTestNow('December 31, 2022');
         $time = Time::parse('December 31, 2020');
 
         $this->assertSame(2, $time->getAge());
     }
 
     public function testGetAgeNextDayOfBirthday(): void
     {
-        Time::setTestNow('January 1, 2022', 'America/Chicago');
+        Time::setTestNow('January 1, 2022');
         $time = Time::parse('December 31, 2020');
 
         $this->assertSame(1, $time->getAge());
     }
 
     public function testGetAgeBeforeDayOfBirthday(): void
     {
-        Time::setTestNow('December 30, 2021', 'America/Chicago');
+        Time::setTestNow('December 30, 2021');
         $time = Time::parse('December 31, 2020');
 
         $this->assertSame(0, $time->getAge());