Remove superfluous comments

Remove a few comments that previously add noise but don't offer a great
deal of value.

Issue gh-8945

crypto/src/main/java/org/springframework/security/crypto/encrypt/AesBytesEncryptor.java

@@ -132,8 +132,6 @@ public final class AesBytesEncryptor implements BytesEncryptor {
 		}
 	}
 
-	// internal helpers
-
 	private byte[] iv(byte[] encrypted) {
 		return this.ivGenerator != NULL_IV_GENERATOR
 				? EncodingUtils.subArray(encrypted, 0, this.ivGenerator.getKeyLength())

crypto/src/main/java/org/springframework/security/crypto/password/StandardPasswordEncoder.java

@@ -83,8 +83,6 @@ public final class StandardPasswordEncoder implements PasswordEncoder {
 		return MessageDigest.isEqual(digested, digest(rawPassword, salt));
 	}
 
-	// internal helpers
-
 	private StandardPasswordEncoder(String algorithm, CharSequence secret) {
 		this.digester = new Digester(algorithm, DEFAULT_ITERATIONS);
 		this.secret = Utf8.encode(secret);