Remove inefficiency in HttpStatus.series()

Prior to this commit, the Series value for an HttpStatus was always
evaluated which resulted in an allocation of a Series array by invoking
Series.values() which makes a defensive copy.

This commit addresses this issue by hardcoding the corresponding Series
within the HttpStatus constructor, thereby avoiding any unnecessary
computations. In addition, a unit test has been added to verify that
all HttpStatus enum constants have a properly configured Series.

Closes gh-22366

spring-web/src/test/java/org/springframework/http/HttpStatusTests.java

@@ -128,4 +128,12 @@ public class HttpStatusTests {
 		}
 	}
 
+	@Test
+	public void allStatusSeriesShouldMatchExpectations() {
+		// a series of a status is manually set, make sure it is the correct one
+		for (HttpStatus status : HttpStatus.values()) {
+			HttpStatus.Series expectedSeries = HttpStatus.Series.valueOf(status.value());
+			assertThat(expectedSeries).isEqualTo(status.series());
+		}
+	}
 }